After I finished adding the CaddMann dual air filter conversion and a TFI injection control module to my Vulcan 1600 classic I decided to tackle the exhaust system. I really like the fat look of the stock pipes and mufflers and started to work out a way to gut them out to improve the sound and get a freer flow of exhaust gas through the system. To that end I looked into gutting the catalytic converter.
First off; the 1600 exhaust system is completely different than the 1500. You cannot simply take a piece of rebar or pipe and knock out the muffler baffles like we used to do. The problem is the honeycomb catalytic converter that is pressed into each muffler; from now on I'll just refer to it as the "honeycomb". If you try to bang your way through, it can collapse and block up the pipe and will be very difficult to remove. A V Twin actually runs better on the street with a little backpressure, so we will remove all of the internal baffles with a hole saw and leave the honeycomb in place to act as a single baffle to provide some of that backpressure. Once you remove all of the other baffles you can shine a light front to back right through the muffler including the honeycomb. Believe me, when we get through, the pipes will sound great flow more exhaust with little or no loss of low end torque, and cost very little of your hard earned cash to boot.
The mufflers must be removed from the bike because we have to cut out baffles from both ends. It is not necessary to remove the entire exhaust system but I would advise you to also remove the rear cylinder exhaust pipe to make reinstallation of the mufflers easier later on. Note that the muffler assembly is heavy so be careful when handling it.
Please remember there are variations in the 1600 classic mufflers and this is particularly true of the 2003 models. Some of the mufflers have three baffles (usually one solid and two perforated) looking from the outlet end, some have two solid and one perforated. Some of the mufflers have a perforated baffle in the inlet end of the muffler and my (Gypsy) '03 had one perforated baffle in one muffler and none in the other.
When using the hole saw with extensions to cut out the baffles please stop when you cut through each baffle and dump out the removed material. Then take a flashlight and look down into the muffler. When the last baffle is cut through you will be able to see the catalytic converter. It looks like a rolled up piece of corrugated cardboard. do NOT try to cut into the catalytic converter; you need it anyway to provide a little bit of backpressure so you don't lose too much low RPM torque.
(A) Shows the three baffles you want to cut out from the outlet side of the muffler
(B) Shows the perforated baffle from the inlet side of the muffler. Cut out this one too and follow the same procedure outlined above.
(C) Shows the catalytic converter
(D) Shows the rear end of chamber (E) which should be drilled out as outlined in the Gutting instructions below
OK. so now you have the muffler set off the bike and it's time open them up. I used a 1-3/16" diameter hole saw on two 12" extensions (Sears item #00920920000 Mfr. model #20920, also available from Amazon) to reach into the muffler pipe, and a slow turning electric drill to remove the baffles. Have someone hold the muffler set flat down on the workbench, insert the hole saw from the rear of the muffler and cut out both the solid and perforated baffles in each muffler until the saw comes up to the honeycomb then STOP. Use a flashlight to see when you come up to the honeycomb. Reverse the mufflers and cut out any baffles that remain. Remember to stop short of the honeycomb. Be sure to shake out all of the junk left over from the cutting out of the baffles. You will be able to see light right through each muffler but we are not finished just yet.
Take a look at the end of each muffler and you will see a plate supporting the end of the exhaust pipe. This is the end of a sound chamber inside the muffler. Stand the mufflers on end and lay out positions for eight equally spaced holes on that plate between the exhaust outlet and the sides of the mufflers. Drill 3/16" pilot holes at each location, then drill them out with a larger drill. I used a 7/16" drill. Not only will this improve gas flow a bit more, it greatly improves the sound of the pipes.
Install the muffler assembly on the bike and be careful not to damage the soft gasket seals inside the muffler inlets. To help prevent damage to the seals (expensive at $15 each) have someone help you align the muffler ends with both exhaust pipes as you push them slowly into place. Bolt the whole works into place and fire up the beast. Remember that the bike will now run leaner so adjust the TFI controller to compensate.
When you ride the bike I think that you will really like the sound, around town or when you get on the throttle hard it sounds great, at steady RPM on the highway it is not much louder than stock.
Gordon "Gypsy" Wallgorski