Master Blaster Glasspacks with Silencers à la Mark T
Submitted by
QueXpress (Normand in QUÉBEC)


Information has been provided on these pages in hope that it will be useful.
Each of these pages contains steps followed to complete certain modifications on my bike.
This is not a shop manual. I am not a mechanic.
I assume no liability for any damages, direct or otherwise, resulting from the use of this information.
If you choose to follow the steps on these pages, you do so AT YOUR OWN RISK.

When I purchased my Valk in June 2002, it was equipped with Cobra pipes. The sound was awesome, but the pipes were blued out, and the power sucked.I managed to locate a used set of Pro-Dyno pipes before the end of the summer. The sound was sweet and the power was noticeable.
However the headers were rusty, and the looks ... well ... I've seen better.After seeing many pictures of glasspack setups, I decided to go that route especially because of the striking look of the
long chrome 4-inch truck stacks on each side of the bike. The straight cuts remind me of canons.
I then examined different glasspack versions and chose to try and assemble the Master Blaster version of
glasspacks because of its versatility. I have added silencers à la Mark T because I find the idea brilliant.
It permits to tone things down very quickly and easily.

Parts/material required:

OEM exhaust system
2 X swage nipples
2 X 2-inch water pipe connectors
2 X glasspacks
4 X 5/16 galvanized carriage bolts (1¼-inch length with nuts, flat washers and lock washers)
Exhaust pipe (2-inch I.D.: about 48 inches, 2-inch O.D.: about 24 inches)
2 X 5/16 welding rods
2 X chrome 4-inch truck stacks
Aluminum paint
Black BBQ paint


Tools required:

Bubble level
Chop-saw (or hack saw)
Paint brush (aluminum paint)
Tape measure
Electric drill
Welding machine (otherwise to be farmed out like I did)
Torque wrench

Note: Click on any image to view the full size picture.

Make a Mark 3 inches from the Header Entry

The front portion of the exhaust can will be used to attach the collector/reducer.If you look at the can you will see spot welds that are approximately 3 inches from the forward edge. These are used to secure dividers inside the can. These dividers section
the can into three chambers in order to keep the exhaust flow from each cylinder separate.If you cut through these spot welds on the forward edge, you will be able to easily remove the dividers from the header side of the can with a pair of pliers, vice grips, etc.

As shown by the arrow in the picture, measure and mark the can approximately 3 inches back from its forward edge (where the header pipes enter).

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Cut on Mark with Chop Saw

If using a chopsaw, just cut through the whole thing.
If using a hacksaw, draw a line around the can just in front of the spot weld (approximately 2 inches from the header pipe entry) and saw through the skin of the can (not through
the dividers). Since the cut is ahead of the spot welds, when separating the front portion of the can from the rear, the dividers will automatically be removed (because they are spot welded toward the rear portion of the can).

Note: At the front of the exhaust can, there are two tabs on each side with rubber
bushing that fit into loops on the back side of the front chrome covers. Be sure to
pull these rubber bushings off and save them for later on when installing the chrome
covers over your stacks.

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Pull Out Separators

As mentioned above, the inside separators are only spot welded in one place at the front
portion of the can. If the can has been cut at 3 inches from the header entry, portions of the separators will be left in the can stub.

Since these are not welded to the bottom of the can, cutting through the spot welds will permit easy removal of the separators with pliers, vice grips, etc.

Pull these three little separators out and discard.

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Exhaust Can Without Separators

Once the separators have been pulled out, the can is ready to receive the collector/reducer.


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Swage Nipple Collectors/Reducers

These swage bell reducers, which have been "discovered" by Master Blaster, work very well.
These fittings, which are used for petrochemical and oil applications, give the system a completely smooth flow. There are no flat spots or ridges to disrupt the exhaust flow. Versatility is possible because of the threaded ends that are used to connect the glasspacks or straight pipes.

Note: These swage nipples, which are usually 8 inches long, are now only 5 inches long.
3 inches have been cut from the bottom (large portion) in order to provide a better fit .

A search on the web for swage fittings indicated that these can be purchased at:
These are also available at:
G-G Valve & Supply, Inc.
PO Box 685
Lake Charles, La 70602
(337) 436-9918 Fax (337) 436-5641
These are called 3 X 2 Standard Swage Nipple, and are $11.90 each.
Note: I have no affilition, nor connection to any of these vendors. The above is for information purposes only.

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Set Header Vertical and Level

Note: You need to use a small bubble level to make sure everything lines up before welding.

Clamp the header straight up and use a level on a few sides of the can to ensure that the
can is vertical.

Set Swage Nipple Square With Can

Set the swage nipple in the can (make sure that it is flat on the bottom of the can).


  • Sometimes there will be a rough weld inside at the bottom of the can stub (location where the stock headers enter the can). The rough weld could keep the nipple from setting straight and flat at the bottom of the can. If tha
    happens you can grind the nipple to fit over the weld/bump.
  • If there is any weld or lump on the outside of the can, grind it smooth in order to ensure that the stack will slip over the can without binding up.
  • Use a grinder with a wire brush wheel to clean the swage fitting and also the inside of the can stub..

Note: The nipples will not be welded to the bottom of the can but inside the outer rim.

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Set Swage Nipple Square With Can

Use the level across the top of the nipple in 4 directions to make sure it is square with the can. Once it is level, check to make sure that the swage fitting is centered.

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Weld the Collector to the Headers

Heat a rod about 5/16 in diameter and wrap around the neck of the nipple on the inside of the exhaust can .
This will be for a filler and then just weld over the filler to the nipple and inside of the can.
Once you have the rod in place, before welding, check the level again just to make sure that it didn't move.

Note: If, like me, you need to have the welding farmed out, it may be a good idea to have the 5/16 in diameter rod in hand. I didn't and found out that the shop didn't have any in stock. Therefore the swage nipple was welded directly to the can (not the best way to do it).

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Threaded connectors

Common 2-inch water pipe connectors can be used to connect the mufflers and straight pipes to the swage collectors.
Cut each of these in half in order to obtain two screw fittings to weld onto the front necks of the mufflers and two for the straight pipes..

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Cutting the Threaded Connectors with a Chop Saw

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Two Sets of Connectors

You will note that the inside diameter of the threaded portion is smaller than the inside diameter of the body behind the threads.

Since the smooth body portion of the connectors are a little larger than the muffler necks, you can use a ball peen hammer to bell out the muffler necks in order to ensure a tight fit. A smooth exhaust flow will then be obtained because the end of the pipe will be behind the threads on the connector.

Slip these connectors over the neck of the muffler and, before welding, use the level again to make sure they are square.


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Cut Silencers From Rear of Can

In order to make insertable silencers from the back baffle section of the exhaust, locate the rearmost spot welds. Cut just upstream of these rearmost weld(s). These cut will be approximately 7 1/8 inches from the rear of the exhaust.

Note: Those 3 spot welds hold the rear baffle dividers inside the can.

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Cut Piggies From Rear of Silencers

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Grind Away 3 Separator Spot Welds

In order to remove the 3 separators at the front of your silencers, grind away the 3 retaining spot welds.

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Remove Separators

The separators can now be twisted out with a pair of pliers.

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Peeling the Silencers: Circular Cut

In order for the silencers to fit freely within the commonly sold 4-inch truck stacks, the exterior skin must be taken off.

A cutting wheel on a grinder can be used (with care) to cut the exterior skin off the silencer at the location shown by the arrow.

Note: Do not cut any deeper than the thickness of the skin. Otherwise the baffles will be damaged (i.e.: the silencer will be ruined).

You will note that there are also spot welds on the "piggie end" of the silencers. These must not be destroyed because they are needed to support the baffles. Cut approximately ½ inch (toward the middle of the silencer) away from that spot weld.

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Peeling the Silencers: Horizontal Cut

If you look at the front end of your silencer, you will note that each baffle is separated by a thin wall. Each baffle and adjacent separating wall must be kept intact. In order to do so, make a mark between a baffle and one of its adjacent little separating walls, and then cut along that mark.. See the red arrows and cutting line in the picture.

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Silencer Ready to be Peeled

The spot welds (A) have been ground away, the circular (C) and horizontal (B) cuts have been completed.


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Peeling the Silencer

It is now quite easy to peel the skin off with a pair of pliers, vice grips, etc.

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Silencer Ready to be Installed

It may not look fancy, but it functions very well.

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Tightly Stacked

If your stacks fit too tightly, you will need to drive them on , and they will be a real problem to get off later on down the road.

I know of two solutions (other than waiting to find a stack that fits freely):
1. You can put a slit in the back side of the stack to make it fit a little looser.
On the stacks, you have to determine the side that will be inside and hidden from view, and just make your slit from the front edge straight back for maybe 2 1/2 to 3 inches, just enough to let it expand a little to slip over the can stub.
2. You can grind the surface around the collector until the required clearance for fitting the stacks is obtained. As shown in the picture, I have chosen this solution..

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Different Components on the Floor

A = Header and front portion of the can
B = Swage collector/reducer
C = Connector
D = Glasspack blank
E = Silencer

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Measure and Mark the Stacks for Cutting

After wrapping the stack with masking tape at the approximate cutting location, a piece of cardboard wrapped around the stack permitted me to make a straight mark around the stack at the cutting location. I have chosen to cut the stacks at 38 inches..

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Cut the Stacks

I have used a 24 TPI (teeth per inch) blade on my hacksaw in order to cut 48-inch stacks down to 38 inches.

Note: The cut was then filed and touched up with high temperature aluminum paint.

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Place Silencer in Stack, Mark and Drill

Since each silencer used to be the rear baffle portion in the OEM system, it already had 2 threaded openings to secure it to the muffler. Place the silencer where you would like to install it within the rear portion of the stack, and mark the location to be drilled. Once drilled, it will be very easy to fasten the silencer to the stack.

Note: Use the bolts from OEM exhaust. One bolt per silencer is enough.

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Silencer Fastened Within Stack

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Types of Glasspacks

Some mufflers come as blanks with no inlet/outlet pipes attached. Some come with the inlet /outlet pipes attached.
Note: The blanks are made to weld directly to the exhaust pipe of a car. The other one is made to slip over the existing pipe and clamp on.

If your mufflers are the blank type, you will need to weld on the short extensions. Mine were blanks, such as shown in the picture. However next time I will purchase them with inlet and outlet pipes attached. It will make things easier.
Note: The blanks that I have used are 10 inches long, with 3-inch cases and 2-inch cores.

Master Blaster mentioned that he uses two types of 12-inch long mufflers (usually purchased from JC Whitney). One has a 3 1/2 inch case with a 2 inch core. The other has a 3 inch case with a 1 3/4 inch core.
They both perform about the same but the smaller has a little sharper tone.
Note: The 12 inch size ensure that these will fit in a saddlebag (in order to take them with you).
Anti-seize should be kept in a ziplock bag. Thus, if the container comes open, it will not make a mess.
Master Blaster has also suggested to keep the components stuck in a pant leg (that has previously been cut into a sleeve. This will keep your bags nice and clean.

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Assembling the Glasspacks

If your mufflers are blanks, you will need to weld a 3-inch neck on each end (i.e.: inlet and outlet). The front neck is required to prevent the shoulder of the muffler body from being in contact with the bolts used to mount the truck stack to the bike frame. The rear neck is required by the swap out tool. You will see this tool later on below.

Lay each muffler body in a channel and level it. Then put the level across the threaded end of the connector in all directions to level it.
Note: If it is welded crooked it will not screw onto the swage nipple.

Note: You need to make sure that these necks are made of 2-inch inside diameter exhaust pipe The removal tool will be made out of 2 inch outside diameter exhaust pipe. It needs to be able to slip into the necks and not be too loose a fit.


Fin Direction Within the Glasspacks

If you look inside a glasspack muffler, you will notice fins (little cups) pointing towards the front in order to catch some of the exhaust. Thus the sound will be muffled. I have chosen to flip the glasspack around in order to let the exhaust flow over these little fins, instead of into them. This gives the exhaust system a more "attitude".


Fabricating the Straights

The straights are fabricated the same way as the mufflers.
Note: I have used a section of 2 1/4-inch exhaust pipe 18 inches long for the straights.


Glasspack Swapout Tool

For a tool to swap them out with, you can use a piece of 2-inch exhaust pipe 18 inches long and drill a 5/16 hole about 1 inch back on each side 180 degrees out.
Put a piece of the 5/16 rod through and let stick out about 1/2 inch on each side making a T wrench.
On the other end, drill it for a large Philips screwdriver to stick through for leverage to break them loose.
On the tail end of the mufflers and the straights, grind a slot straight down to fit the T tool, make it about 2 1/2 to 3 in deep.
This is on each side 180 degrees apart.

Note: The picture shows straight pipes on the left, the swapout tool in the middle, and the packs on the right hand side.

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Anti Seize:

You have to use anti seize on the threads or they will freeze together.
If that happens you can pull the stacks and get a pipe wrench to break them apart.

Note: Liberally use anti-seize, change them on a weekly basis, and they will work fine.


Mark Position of Front Covers

In order to obtain a smooth flow of chrome front to back without the seam that shows on the stock setup, the stack should slip about ¼ inch under the front chrome cover that is over the header pipes.
Note: You have to be careful. If you put it too far forward, the covers wont fit back on.

As shown in the picture, I have installed the front cover and marked the location of its edge on the exhaust can. After removing the front cover, another mark was made ¼ inch ahead of the cover mark. This will be the location of the front edge of the stacks


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Mark the Stacks for Drilling

Slip the truck stack over the can. Position the front edge of the stack on the mark that has been made on the can in the previous step.
Once you have it positioned, use a grease pencil and mark the stack through the exhaust hanger mount holes
Note: Masking tape wrapped around the stack would permit you to use a pencil pen, etc.

Remove the stack and drill two 3/8-inch holes where you have marked it.

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Galvanized 1¼ inch X 5/16 Carriage Bolts (with nuts, flat washers and lock washers)

To mount the truck stacks, round headed galvanized 1¼-inch X 5/16 inch carriage bolts (along with galvanized nuts, washers, etc.) have been used.
Note: These bolts must not be too long. Otherwise they will rub on the swing arm.


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Bolt Heads Inside the Stacks

Put in the carriage bolts with a washer, lock washer, and nut. Tighten them until the heads of the bolts fit flush inside the stack.

Note: In order for the round headed carriage bolts to mount the stacks to the hangers, 3/8-inch holes were drilled into the stacks. Since these holes are slightly smaller than the little square portion of the bolt, when the carriage bolts are tightened down, the little square is force fit through the hole. This prevents the bolts from turning while being tightened.

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Bolts Outside the Stacks

This is how the bolts sticking out of the stacks will mount into the frame.

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Glasspack Tweak Tool

If the swage fittings have been welded perfectly level within the cans, and if the connectors have also been perfectly lined up with the mufflers and straight pipes, everything (stacks included) will line up perfectly.
If these are not all perfect, a tool can be fabricated to tweak the headers a little. A reducer (2½ inch to 1¾ inch) screwed onto a 4-foot pipe made a great tweak tool. As shown in the picture, the rear of my stacks were a little too high. A little nudge downward fixed that pretty quickly.
Note: If the nudge is to be given sideways or upwards, it is highly recommended to have someone brace the side of the bike for you. It is quite easy to topple the bike over with such a pipe. I found that out pretty quickly while tweaking one of the exhausts. I was lucky. The bike simply moved sideways. Two minutes later, I had someone holding the side of the bike for me ...

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Fitting the Cover Over the Right Stack

The front chrome cover is relatively easy to install over the left stack. However it's a bit more difficult on the right side. As shown in the picture, the brake pedal, the foot peg and a cover just above these are in the way.


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Wire to Clear the Pipes

Remove the chrome cover and then remove the two bolts that hold the whole brake assembly to the frame.
While covering the bike with a towel or rag, use a piece of wire to lift and hold the whole assembly up and out of the way.
There is enough slack in the brake hose to let you lift these parts high enough in order to be able to install the front chrome cover over the stack
Note: Before cutting the exhaust can, you had removed little rubber bushings from tabs at the front of each can.
These little rubber bushings must now be placed over the two tabs on the exhaust can in order to fit into the loops on the inside portion of the chrome cover..


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Chrome Is Good for You!

There is now a nice smooth flow of chrome front to back without the seam that shows on the stock setup.

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Sound Files:


nice mellow sound 10-inch Glasspack
  Glasspack + Silencer
louder with a bark in it Straight Pipes

Straight Pipes + Silencer

very loud deep roar Swage Collector only
  Swage Collector only + Silencer

Hats off to Master Blaster for patiently explaining each step (many times) of his glasspack system and also a special thanks to MarkT for coming up with the silencer idea.