Question about exhaust

[mazdaspeedpower]

Ok, if I where to get a custom exhaust done for myself, what diameter would you suggest? I will be looking for a place locally that will mandrel bend instead of weld or crush bending. I haven't decided wheather I will put a new high flow cat or just eliminate it and just go straight back to the muffler....if I did that, I'd make sure I kept the stock, and made sure it was easy enough to reinstall for any emissions and s***. Keep in mind I will not be going too crazy with power, I'm just looking for something larger than stock that will work well with the car. I don't need anything crazy, but whats a reasonable size for a slightly modded MSP. Stock boost to slightly higher(lower than 10psi) with IC/Hardpipes/CAI

Also, what muffler would you recomend for the best performance/sound. I don't want anything ricey sounding, but I mean, if it performs better than a deep sounding one who cares. Performance over sound. Please give suggestions and input and s***. Also links would be great too, thank you.

 

[Striker187]

2.5" piping will be more than enough. as for the muffler....check out the exhaust thread. you're sure to find something you like. as for performance, i believe turbo performance magazine published an article a year or so ago comparing different exhaust setups on a wrx....apexi, 5zigen, blitz, hks, tanabe, etc. the range in hp was maybe 4-5 hp. nothing that's gonna make a big difference.

the article is here: http://www.turbomagazine.com/tech/0212tur_exhaust/

i used it mainly to judge how loud my exhaust was gonna be.

 

[jeffmsp]

I got a 3" catback and felt no gains. Then I added a 2.5" downpipe and highflow cat and it goes pretty good. I am using the stock MSP axleback, so it is not much louder than stock. If you are looking for some more "technical" explanations, check out this link: http://www.msprotege.com/forum/showthread.php?t=67805

 

[geomatics_tech]

I got a 3" catback and felt no gains. Then I added a 2.5" downpipe and highflow cat and it goes pretty good. I am using the stock MSP axleback, so it is not much louder than stock. If you are looking for some more "technical" explanations, check out this link: http://www.msprotege.com/forum/showthread.php?t=67805

Would using the stock cat back be much worse than using just the stock axle back with a 2.5" down (s and j) and mid pipe? Or would it be beneficial to run 2.5" piping to the axle back?

shaun

 

[Striker187]

definitely run 2.5" piping to your axleback. forget the stock crap....replace as much of it as you can.

 

[orng1]

It really epends what you are looking for. Performance wise anything mandrel bent and bigger will be better. As for the sound, I personaly havent heard a bad sounding turbo car of any kind with a performance exhaust. They just sound deep. I'd go 3" if possible, I've got 3" with a strait through muffler from the cat and it still seems to quiet for me. Soon I'll have the cs down pipe hopefully it will add some sound. Good luck.

Bob/orng1

 

[Striker187]

trust me, that downpipe is gonna make a world of difference.

 

[HASE]

I had a custom exhaust done and it made a big difference. I have a 2.5 inch manderal bent from the spring bolts back. Had the new arvin meritor seamless / stainless high flow cat installed (No CEL's in 2500 miles) and a standard Magnaflow Muffler. Sounds good and deep. Not ricey at all. I am actually getting about 2mpg better when I am not driving hard.

 

[sXe]

for the power you're talking about a 2.5 will be plenty for what you need

just make sure you get that downpipe changed out

 

[JDM Sam]

For the bang for the buck do a 2.5 inch pipe from the J-pipe to the stock racing beat muffler, catless. Makre sure to get a spark plug non fouler.
Sounds good, relatively low in cost, good power gains.

 

[mazdaspeedpower]

For the bang for the buck do a 2.5 inch pipe from the J-pipe to the stock racing beat muffler, catless. Makre sure to get a spark plug non fouler.
Sounds good, relatively low in cost, good power gains.

are you suggesting I keep the stock muffler, and go with an exhaust without a cat? I kinda don't want get too much heat for no cat, cause I know the cops here can and will arrest you for not having a cat on the car...thats kinda why I wanted to keep a highflow cat. I know the cat is what kills the power the most, but I kinda wanta remain kinda legal. Also, how will the stock exhaust sound? I know my main goal is power, but will the stock exhaust sound ok/good....as important as the power is, I do wanna sound more aggressive than stock also.

Thanks for the help people, keep it coming.

 

[JDM Sam]

are you suggesting I keep the stock muffler, and go with an exhaust without a cat? I kinda don't want get too much heat for no cat, cause I know the cops here can and will arrest you for not having a cat on the car...thats kinda why I wanted to keep a highflow cat. I know the cat is what kills the power the most, but I kinda wanta remain kinda legal. Also, how will the stock exhaust sound? I know my main goal is power, but will the stock exhaust sound ok/good....as important as the power is, I do wanna sound more aggressive than stock also.

Thanks for the help people, keep it coming.

stick a 2.5 hi flow then. same setup. works fine, makes power, and sounds good.
A j-pipe back 2.5 inch mandrel bend no resonator and 1 cat to the stock muffler will be sufficient for what you require.

 

[arkitek]

Good thread here. So if I want it as quiet as possible, just add a resonator pipe then.

What is the stockpipe size cat-back anyway?

How about keeping everything stock from cat-back and just replacing downpipe, hiflow cat? Might try this first to see.

 

[ChopstickHero]

I got a 3" catback and felt no gains. Then I added a 2.5" downpipe and highflow cat and it goes pretty good. I am using the stock MSP axleback, so it is not much louder than stock. If you are looking for some more "technical" explanations, check out this link: http://www.msprotege.com/forum/showthread.php?t=67805

thanks... good read.

 

[Tito1]

So what is the ID of the the stock muffler inlet? And is the cat back 2.5"? I though I read that somewhere.

 

[mazdaspeedpower]

stick a 2.5 hi flow then. same setup. works fine, makes power, and sounds good.
A j-pipe back 2.5 inch mandrel bend no resonator and 1 cat to the stock muffler will be sufficient for what you require.

thank you for your help..

EDIT* Upon some further research, what I'd be looking at doing is a midpipe with highflow cat and a downpipe. all of which bolts right up to the stock catback. This seems to be what gives the most gain, as I already knew changing the catback really gives no gains, just changes the sound. I guess I'll go 2.5", as it seems to be a good size. I'll update you when things happen(a few weeks), with some pics and s***.

 

[mazdaspeedpower]

ok, so tomorow I'm gonna visit a few shops, and check some pricing and such. Hopefully I'll be able to get a downpipe to stock muffler at 2.5inches for a reasonable price. what is the diameter of the stock muffler inlet and outlet?

 

[JDM Sam]

The Racing Beat Muffler inlet is 2.25 but a 2.5 flange and gasket will mate up fine to it.

 

[mazdaspeedpower]

but wouldn't mating a 2.5 to a 2.25 be kinda pointless? Wouldn't I just be pushing the restriction further up the line, still restricting the flow, just further from the source.

 

[Striker187]

bingo. granted with what you'll be replacing takes out most of the restriction in the exhaust system, if you want the best gains, go with a consistent size piping throughout.