modifying stock muffler

[Joe ltx-le]

Hey all , summers over its almost time

I am looking for input on DIY modifying the stock muffler for free flow. I know there are many company's that will do it but prices are crazy. Has anyone done it themselves?

Thanks

 

[NYTurbo]

yeah not cheap, but most enlarge pipe in and out and modify the internals . Quite a bit of work . The pipe in is a considerable amount of effort.

 

[BTP]

I turned my stock muffler to a 3" and its very quiet.

 

[yamamarc]

I have the hurricane trail muffler and riveted the stock muffler heat shield on it !! It fits perfect!

 

[Turboflash]

I turned my stock muffler to a 3" and its very quiet.

flo
I think it's good to keep in mind its not only the diameter of tubing in an exhaust system but really what performance needs is FLOW. So, increasing the stock muffler outlet to 3" might, on paper, sound like a great change to make but my question is, what about all the internal passages and tubing? Can it all flow what a 3" outlet can flow (that means starting from header through head pipe to turbo housing into muffler head pipe, into muffler internal baffles, and out the outlet)? If there is any place in the whole exhaust stream where it can't flow what a 3" outlet can flow, there is a restriction (and the 3" outlet pipe doesn't matter). An exhaust system will only flow as much as it's smallest orifice in the entire system.
I think this might be what NYTurbo is alluding to and maybe why the vendors who modify stock mufflers charge what they do. It's allot of work to go inside the stock muffler and change all those orifices to 3" (or 2.5" or whatever).
Also, even if a 3" outlet pipe helped (that assumes all the rest of the internal parts in muffler can flow what that 3" outlet pipe can flow), I've read here in TY that in some places, law enforcement is simply measuring the size of the muffler outlet and comparing that to the OEM stock specs and if it's not the same, you get a ticket even if your exhaust system sounds stock (has same dB readings as stock).

 

[NYTurbo]

Yeah there is more to it that changing the inlet and outlet pipes. Anyone that has cut a stock muffler open will realize this.

 

[74Nitro]

I've opened up my stock muffler, but there isn't much baffles inside. I removed what little there was and it does add a small amount of sound(that I like), but I doubt has little effect on power.

 

[Fast]

I turned my stock muffler to a 3" and its very quiet.

What tune do you run

 

[BTP]

Hurricane was 290 and then went to header 300 with 4 bar map.

 

[Attack gt]

If I ever come across a stock muffler, I will take and cut it open and take pics of the internals. I would like to experiment with modifying one and see if I can come up with a DIY stock modified muffler that could be done on a budget. It is so expensive to send out and have one done!

 

[ROCKERDAN]

If I ever come across a stock muffler, I will take and cut it open and take pics of the internals. I would like to experiment with modifying one and see if I can come up with a DIY stock modified muffler that could be done on a budget. It is so expensive to send out and have one done!

The work is in the outlet mostly. Making the outlet(turbo to muffler) a larger size is much more difficult then adding larger tubing into the muffler itself.

Dan

 

[GodSpeedSWE]

I turned my stock muffler to a 3" and its very quiet.

Any pictures?

 

[Turboflash]

You changed the outlet or all the passages inside the muffler?

 

[Fleecer]

flo
I think it's good to keep in mind its not only the diameter of tubing in an exhaust system but really what performance needs is FLOW. So, increasing the stock muffler outlet to 3" might, on paper, sound like a great change to make but my question is, what about all the internal passages and tubing? Can it all flow what a 3" outlet can flow (that means starting from header through head pipe to turbo housing into muffler head pipe, into muffler internal baffles, and out the outlet)? If there is any place in the whole exhaust stream where it can't flow what a 3" outlet can flow, there is a restriction (and the 3" outlet pipe doesn't matter). An exhaust system will only flow as much as it's smallest orifice in the entire system.
I think this might be what NYTurbo is alluding to and maybe why the vendors who modify stock mufflers charge what they do. It's allot of work to go inside the stock muffler and change all those orifices to 3" (or 2.5" or whatever).
Also, even if a 3" outlet pipe helped (that assumes all the rest of the internal parts in muffler can flow what that 3" outlet pipe can flow), I've read here in TY that in some places, law enforcement is simply measuring the size of the muffler outlet and comparing that to the OEM stock specs and if it's not the same, you get a ticket even if your exhaust system sounds stock (has same dB readings as stock).

Good info here! I ran SMM muffler at a cost of $350 to get it modified. TD SQ makes more power, pulls more rpm than SMM and is a better investment imo. SQ is best all around muffler when comparing noise, power and you can put stock shields. The extra 5hp at 300hp running free flowing muffler isn't worth the extra noise imo!!!

 

[JayM]

Good info here! I ran SMM muffler at a cost of $350 to get it modified. TD SQ makes more power, pulls more rpm than SMM and is a better investment imo. SQ is best all around muffler when comparing noise, power and you can put stock shields. The extra 5hp at 300hp running free flowing muffler isn't worth the extra noise imo!!!

I want to put the stick shields on the SQ, did you do it and if so any pics?