Philly, this old post should give you a general idea of how I attach a muffler to a stock header.  My bike uses a Mac header which is significantly different.  It's much easier to fit a muffler to the Mac header because the header is straight and does not have a step that reduces the OD.  In the old post, I show how to fabricate an adapter and shim it to fit the stock header.  It's not too hard but you will need a MAP Gas torch and a bench vice along with other basic tools.  See replies #3 thru #20 of this old post.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1623048749

so -- funny story. I started brazing together my own mid pipe adaptor as DBM outlined in the post he shared. First time brazing and I decided to set up my brazing station on my back patio -- my plastered back patio -- a material I know have come to understand does not enjoy high, direct heat being applied, due to a phenomena known as "spalling", in which moisture trapped under the surface needs to expand when heated past the boiling point.... Violently.

Baseball sized chunk of plaster exploded directly into my face. Fun times.  

Anyway I did get the shorty cherry bomb on there eventually, and found it too open. Back to the drawing board.

Surviving Philly wrote on 08/03/25 at 04:52:48:


Or back to STOCK.

On my older LS this is the exhaust I fabricated and am very happy with as to performance and sound. It is a VooDoo slash cut muffler. I built the interface to header with a baffle in it and installed a "bolt in" catalytic baffle inside the muffler at the rear.

I built a mounting bracket to position the muffler as a 3/4 down turn, rather than exhaust exiting at 90 degrees. This repositions the exit of the  exhaust down rather than out at side which substantially changes the sound.

The adapter is just exhaust pipe from Napa, I took it to muffler shop and had them bend it and then expand it to fit header. The smaller cut lines are to allow for greater compression in fit utilizing a thin sheet steel sleeve to assure seal.

It is much more free flowing. You could add a bit of back pressure by through bolting a fender washer onto the catalytic baffle to force gas around it at the exit. I have run this set up for 6 plus years and am very happy with it.

On my S40 I have the Delkelvic exhaust and it is different. That bike has a more "2 stroke" feel to it, as best I can describe it. I was not completely happy with the look of it out of box and built a new mounting bracket for it to rotate the muffler. I added a catalytic to the rear of it also to improve the sound and add a bit more back pressure which helped minimize the feel of it. Thought though is it needs a bit more back pressure.

Hey Philly.  I know you have that VooDoo or whatever straight thru turn out style muffler (non-muffler).  I was just thinking if you can't get the cherry bomb to cooperate, maybe you could find a good used stock exhaust.  Somebody on this forum probably has a takeoff laying around somewhere.

SoC - I'm not understanding why you are trying to install back pressure.  With the stock cam, there is no scavengering benefit to be gained.  And the inside diameter of the stock header pipe is already almost undersized.  I can somewhat understand if you are trying to reduce sound volume.

Dave, I’ve watched countless videos and read numerous articles and partial books about exhaust system design - back pressure, scavenging, reversion, velocity, flow….

In caveman terms:
Back pressure: Bad
Reversion: Awful
Flow: Good
Scavenging: Great
Velocity: Mostly determined by pipe diameter.

A certain level of velocity is needed to support scavenging.  Scavenging can only occur if there is valve overlap.  As mentioned in the video, a certain level of velocity is needed to prevent nasty reversion.

The optimal diameter of the primary header(s) is key to creating an appropriate amount of velocity.  Very simply, faster velocity in the primary headers supports scavenging and prevents reversion.  Beyond about the first 18-24” of primary headers, trying to impact scavenging is almost futile. Preventing reversion can still be somewhat be addressed past the primary headers with mufflers/baffles/exhaust exit size.

I’m not sure how big singles are really any different in all this.  DBM’s muffler shoot out and other testing with larger diameter header pipes on a hot rod proved that there is such a thing as too big.  While a 2” header pipe will flow tremendously well and reduce back pressure beyond what is necessary, velocity dropped so far that reversion became a problem and hindered low/mid range performance.

Maybe it’s semantics, but I have a knee jerk reaction when someone says they want to add back pressure.

I’m trying to work through this issue on my own bike.  The primary headers on my aftermarket exhaust are 34mm ID.  The stock headers are about 29mm ID.  I’ve lost some low/mid range torque and throttle response and gained some power up top.  Better flow and less back pressure, but it  lost some of the velocity to support optimal scavenging.  Installing baffles at the end of the mufflers helps a little, but they can’t correct the fact that the primary headers don’t allow enough velocity.  The performance above 6,000rpms is beastly (like a drag strip bike), but putt putting around under 4,500rpms and gently accelerating has been muted.  It’s not the worst problem in the world to have - the bike still pulls nicely and smoothly down low.  Some people might actually prefer the more gentle nature down low.

Dave wrote on Yesterday at 09:28:40:


I agree with this.  Maybe if I stop derailing the conversation with comments about my bike, maybe we can get some constructive points made about the LS650.

If SoC wants to add back pressure, that’s his business.  If he meant something else, clarification would be helpful.

I’m going to let this rest with “adding back pressure” to the stock system with a primary header that is barely adequate in terms of flow isn’t a great idea for performance.  If you end up adding a little back pressure to keep noise down that’s understandable, but a compromise to overall performance has probably been made.