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View Full Version : Exhaust woes .... :(


ChopstickHero
10-20-2005, 02:11 PM
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
10-20-2005, 03:06 PM
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
10-20-2005, 03:55 PM
So would you notice that much of a difference if you ONLY replace the 's' pipe and keep the rest stock?
hazeXban
10-20-2005, 04:03 PM
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
10-20-2005, 04:09 PM
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
10-20-2005, 04:11 PM
Get the GHL turboback with cat, resonator, and tell em to make the muffler quieter. Mines pretty quiet.
goku4658
10-20-2005, 04:15 PM
u still using the ghl muffler?
TampaBlackMSP
10-20-2005, 04:16 PM
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
10-20-2005, 04:20 PM
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
10-20-2005, 04:22 PM
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
10-20-2005, 04:26 PM
damn i want a quieter one...shit i don't even have the flex pipe
terbow
10-20-2005, 04:31 PM
well i went through 3 rear sections cause the hangers kept breaking , they just figured it out. so now its all good.
aMaff
10-20-2005, 04:34 PM
electric bypass (first)
ChopstickHero
10-20-2005, 04:45 PM
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
10-20-2005, 04:46 PM
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
10-20-2005, 06:56 PM
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:

http://www.msprotege.com/members/Dr.Sound/cats/Cats.jpg
ChopstickHero
10-20-2005, 08:17 PM
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
10-20-2005, 08:49 PM
cool
i'm ordering it on the 26th
msp35
10-21-2005, 01:05 PM
GHL all the way. With the stock muffler, it's not loud at all until you get on it.
Notorious_V.I.C
10-25-2005, 11:54 PM
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??
Dr.Sound
10-26-2005, 02:39 PM
i'm not sure what cat GHL uses, but the magnaflow one is CARB legal, so it will pass smog in cali.
i havent personally tried it, but that's what it says on their website.
Notorious_V.I.C
10-26-2005, 04:44 PM
I'll have to contact GHL then to see what kind of high-flow cat they use. Does anyone know for sure that the new full dps from ghl come with a flex now??
Matrix
10-26-2005, 04:53 PM
Dr. Sound - Do you have a part number for that cat? Also, does it come with an O2 bung in it or does one have to be welded in?
Thanks.
livelyjay
10-27-2005, 08:25 AM
Dr. Sound - Do you have a part number for that cat? Also, does it come with an O2 bung in it or does one have to be welded in?
Thanks.
Cats usually don't have bungs on them, it's the exhaust piping before or after that has the bung.

Vibrant comes with two O2 bungs, one before the cat (for WBO2) and one after the only cat, for the second stock O2. That combined with the 3" j-pipe back stainless piping means for a pretty good deal at $800. I'll be getting my custom estimate next week and see if I should go that route or with the Vibrant.
Notorious_V.I.C
10-27-2005, 11:21 PM
I was wondering would the exhaust system pass smog in cali if I take one cat out of the stock downpipe and put it on another downpipe like the ghl or something?? I'm guessing power might be reduced.???
MP503
10-27-2005, 11:29 PM
when smog time comes around, just bolt the stock shit back on. Shouldnt take more that a few hours at the most. Can be done with hand tools and a floor jack with stands. Same thing if you get pulled over and get a ticket.
Notorious_V.I.C
10-28-2005, 01:43 AM
Wait! You can get pulled over for even having one high-flow cat??? But get this what if I have the GHL Full Downpipe? cause the thing is I have a 3inch catback so i plan to get the ghl with 3inch flanges, i don't think the stock down-pipe can fit onto the s and j pipe thing that comes with the ghl dp....sorry if it sounds rude....

just tryin to clear things up...
Dr.Sound
10-28-2005, 02:44 AM
u CANNOT touch anything that has to do with emissions.
in Cali there is a $1,500 fine per cat.
Notorious_V.I.C
10-28-2005, 02:57 AM
damn this sucks ass.......so if i get a dp w/ a high-flow cat i can still be fined???this shit sucks f -in california....damnit
livelyjay
10-28-2005, 07:05 AM
damn this sucks ass.......so if i get a dp w/ a high-flow cat i can still be fined???this shit sucks f -in california....damnit
You could get the CorkSport dowpipe (does not touch cats at all). Then have a shop make you a pipe with high-flow to replace the mid-pipe (between the downpipe and cat-back). Then when emissions time comes around (or you get pulled over and the dick cop gives you a ticket for it) throw the stocker back on. Swapping would take about an hour with hand tools.