Exhaust woes .... :(

[ChopstickHero]

So I've been looking for an exhaust for a while now. It's the only bottleneck in my system right now. I'm trying to balance the factors of emission compliance, noise, performance, price and looks. Probably most important is emissions. In CA it's a hefty fine if they catch you, and this is my daily driver, so I can't be decking this thing out with hi-flow everything and no cats. My car looks totally stock in appearance and you can see the mods that I have in my sig. I need something that's both functional, mostly legal and performance increasing.

So would it wise to get a larger diameter S and J pipe (like the Corksport ones), KEEP both cats in the mid-pipe and then get a larger diameter cat back exhaust? Or is there totally no point for putting in the downpipes since the stock cats are so restrictive. I think whatever catback will show small gains, but not much. If anybody has PASSED CA emissions on a good high flow cat, please post up! Thanks in advance for your suggestions.

 

[Dr.Sound]

cats are very restrictive, i've had both a catless downpipe and one with hi-flow cat.

difference between stock and catless was huge.
difference between catless and hi-flow cat was almost non existant.

go with a 2.5" or 3" downpipe with a hi-flow cat, and leave your stock catback.

downpipe will give you about 15 whp at stock boost (more at higher)
catback will give 1 or 2 whp.
with stock catback sound will not change.

BTW, the cat i had on my protosport downpipe was a CARB approved smog legal cat designed for 4.6 liter V8s. it had a CARB number stampped on the bottom of it.

 

[Stormtrooper77]

So would you notice that much of a difference if you ONLY replace the 's' pipe and keep the rest stock?

 

[hazeXban]

You won't find a CARB legal exhaust for our cars. That being said if your car is under warranty its not legal for you to replace the cats IIRC.

 

[ChopstickHero]

cats are very restrictive, i've had both a catless downpipe and one with hi-flow cat.

difference between stock and catless was huge.
difference between catless and hi-flow cat was almost non existant.

go with a 2.5" or 3" downpipe with a hi-flow cat, and leave your stock catback.

downpipe will give you about 15 whp at stock boost (more at higher)
catback will give 1 or 2 whp.
with stock catback sound will not change.

BTW, the cat i had on my protosport downpipe was a CARB approved smog legal cat designed for 4.6 liter V8s. it had a CARB number stampped on the bottom of it.

yeah i figured the only way around it is to get a good hi-flow cat of some sort... passing emissions is another issue i guess. what the diameter of the stock Mazdaspeed catback? I remember reading it's 2.25", anybody verify that?

 

[terbow]

Get the GHL turboback with cat, resonator, and tell em to make the muffler quieter. Mines pretty quiet.

 

[goku4658]

u still using the ghl muffler?

 

[TampaBlackMSP]

DO NOT go ION if you're worried about noise (for emissions it's fine however-race cat) - my gains with the 3" ION turbo-back were HUGE, but the noise (even with the resonator) may wear on you....it does to me now and again, and I've had my system for awhile now...

 

[ZenProtege]

are you allowed to have a cut out w/ CA emission laws? If you can that might be a good option. I don't know if you can fit one between the DP and cats on the stock exhaust

 

[terbow]

u still using the ghl muffler?

Yup, actually i had to get another one cause they forgot to put a flex pipe in the exhaust. and i asked em to make it quieter for me and they said no problem. and made it quieter some how

 

[goku4658]

damn i want a quieter one...s*** i don't even have the flex pipe

 

[terbow]

well i went through 3 rear sections cause the hangers kept breaking , they just figured it out. so now its all good.

 

[aMaff]

electric bypass (first)

 

[ChopstickHero]

Get the GHL turboback with cat, resonator, and tell em to make the muffler quieter. Mines pretty quiet.

yeah, i know somebody that is selling theirs for a fairly decent price. but it doesn't have a flex pipe.

My original plan was to get teh MAM S/J combo with a flex pipe, mid pipe with high flow cat and a Greddy SP2 catback. But now that MAM is under reorganization, i dunno if they're every going to produce the downpipes.

electric bypass (first)

Thought about that! i wouldn't mind getting one heheh... does anybody have the QTP electric bypass?

 

[terbow]

IF it doesnt have the flex pipe it may be ok., but they are REALLY good customer support and will send one out within 3 days. They're customer support makes it worth it.

 

[Dr.Sound]

yeah i figured the only way around it is to get a good hi-flow cat of some sort... passing emissions is another issue i guess. what the diameter of the stock Mazdaspeed catback? I remember reading it's 2.25", anybody verify that?

yeah, dont cheap out on a cat.
i did a lot of research when i was getting my cat and this was one of the best out there. the only better ones were metallic cats that are used on hi-flow systems for corvettes, but they are 200-300 a piece.
i got a Magnaflow stainless steel hi-flow cat.
$90

by the way Mike, i'm selling that downpipe when i get Vibrant.

this is it:

 

[ChopstickHero]

Hey Vic ... yeah, that sounds good, lemme know when you get the Vibrant, i wanna check it out. you gonna install it at your place? i'll come help.. haha...

 

[Dr.Sound]

cool
i'm ordering it on the 26th

 

[msp35]

GHL all the way. With the stock muffler, it's not loud at all until you get on it.

 

[Notorious_V.I.C]

I have a 3inch catback, and i'm stuck on what to do to make it a turbo back either GHL full dp, MAM or cork sport..... I am having trouble with finding out which is good for [assing emissions. Hey Vic will that Magnaflow stainless steel hi-flow cat pass emissions? it says smog legal. I wonder if i get the ghl if i can get them to put in a smog legal hi-flow cat....what kind of cat does GHL use??