I know that the piping after the headers are a bottle neck; however if I was to change the piping ( test pipes, y-pipe, mid pipe) and keep the stock muffler would I be able to expect signifigant gains and how would it compare to an aftermarket cat-back exhaust system?; is it a large or marginal difference?

 

i hope you have a better chance of folks repsonding cause i asked this nearly identical question and no one volunteered......imo, it should be ok once the secondary flap/outlet opens?


04 6mt Sedan / stock airbox mod / z-tube / k&n panel filter / crank pulley / 18" r/h c2s / s-tein springs

 

The Y pipe alone may give you some benefit, going to high flow cats or test pipes should give you significant benefit since it seems to be the consensus that the stock cats are the biggest bottle neck in the exhaust system.

I haven't heard of anyone changing the mid pipe on the coupe without changing the muffler. Changing the midpipe on the sedan is supposed to work pretty well though.

 

here's an idea to kick around..........IF the oem muffller is too restrictive with the additon of the y-pipe and/or test pipes, can't the tailpipe opening made bigger? ie. getting rid of the two tail pipes and welding on one big tailpipe.


04 6mt Sedan / stock airbox mod / z-tube / k&n panel filter / crank pulley / 18" r/h c2s / s-tein springs

 

It's not that simple. I believe that our mufflers are staged so that 1 output pipe is used up to a certain limit of flow, and then the other pipe kicks in. If you look at your muffler (on a sedan), you'll see that one tip is getting more discolorization than the other as a result.

I think the easiest way of freeing up the flow would be to just remove the muffler altogether - gotta love that sound;-)

Seriously, from what I've read in other posts, the stock muffler is actually pretty good and doesn't present a major flow upstruction. All the gains to be made happen upstream (headers, cats, y-pipe, and mid-pipe.


-townsley-
03 Premium BS/Willow 5ATS w/mods

 

you would most likely need to change out the exhaust. But you should either why cause it makes the car look better and sound a lot much better and the rpm response is siiiick =)

 

I told you what you needed to do already lol, get a full catback.. it will save you money and time of mixing and matching parts, yes a new y pipe, mid, cats or test pipes will free everything up, but the rear section muffler is still restrictive compared to other exhaust systems!!


Martin
2003.5 BS G35
Nismo Aero/Sport Package
0-60 5.4 - 1/4 Mile 14.16 *GTech* and on 19's!!

 

Stock muffler is somewhat restrictive.....but Damn Heavy!

"I like you.....You remind me of myself when I was young and foolish"