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Attitude Adjustment Eng.
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Discussion Starter · #1 ·
Hey all, Need some help.
Tried to find the answer to my question here but just could not find it. So I'll start a thread. So I thought I'd ask all you experts.
Question:
I have no engine mods yet (YET!) and I want to do my exhaust.
I want to do away with my muffler. I've seen it before on other cars and as far as emissions it doesn't matter. I live in Cali so I cannot remove my CAT.
I don't want it to be crazy loud but I do want it to sound good.
What would be the best way to go about straight piping my '04 RSX-S.
I want a bigger pipe than stock so how much would I have to replace?
All the way up to the header? Anyways, I'm thinking Header, CAT, RES, and straight pipe.
Good Idea? Bad Idea?
I also have to be Cali emissions compliant.
Any input pro or con would be helpful.
 

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Greddy SP2 for exhaust...cat back, straight through design. Sporty sounding, can tell its not stock, but wont attract alot of unwanted attention from police. I dont know the Cali laws too well, so I'm not sure what to reccommend for Header...a shorty header I suppose, but you wont gain a whole lot off of it with the cat in place.

Another thing for your info..cat back exhaust do hardly anything on our cars....especiallya stock one. You wont feel the gains really. If your looking for some more power I'd start with a CAI
 

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Engineering
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geat a shorty header, high flow cat (one that has inlet/outlet the same size as your piping), resonator (inlet/outlet same size as piping), and then straight through piping. what are you looking to do with your car? NA? if so then 2.5" piping
 

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Attitude Adjustment Eng.
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Discussion Starter · #4 ·
Thanks for the reply.
I intent to do allot of stuff, but we all know how that goes.
Maybe turbo later on in the game.
For now though, I just want to get rid of the muffler without it sounding crazy loud and crappy. Remember, My engine is stock. I have the CAI in thought. Def need that.
How would this set up perform and sound? For this setup, I'm not going to spend that much. I was reading some posts on some OBX RH's that were decent and not as expensice as a DCRH.
Any thoughts?
 

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Engineering
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with the 2.5" piping, you will lose quite some backpressure. i know i did, and i also have an Injen CAI. however, the high end hp you gain from the 2.5" piping is incredible. certainly worth the loss of backpressure and low end power/torque in my opinion. with a 18" or 22" resonator, this setup will not be too loud. remember, you get what you pay for, so be weary of the OBX RH. i'd just go with the DC, its just that, DeCent. once you get the RH though, your car should balance out since you'll be putting out alot more power so there won't be a much noticable loss in backpressure
 

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Attitude Adjustment Eng.
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Discussion Starter · #6 ·
Are you in Orange Co. California?
I need to pay attention to Ca. Emissions Laws.
What type of Res. should I get? (Wool filled, glass filled, etc)
What about the stock CAT, is it 2.0" If I go with a 2.5 INlet/Outlet will I need to stay away from flow through to keep my emissions legal? Also, what type of gasketing is best?
So Let me see if I have this right.... RH (2.5 I/O) - CAT (2.5 I/O) - Res. (2.5 I/O) - 2.5 Straight pipe (maybe with Tip). Do they have pipe stock that has a bigger tip than 2.5 on the outlet end? Maybe 3-4" ?
Also, I don't have a whole lot of acess to a shop. Are all of these pieces available with 2.5" flanges?
Just trying to wrap my head around this before I move forward.
 

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cant have a race header and a cat really man....most race headers replace the cat. A select few you can swap in a high flow cat tho but you wouldnt wanna be caught like that in Cali
 

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Attitude Adjustment Eng.
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Discussion Starter · #8 ·
cant have a race header and a cat really man....most race headers replace the cat. A select few you can swap in a high flow cat tho but you wouldnt wanna be caught like that in Cali
Caught with the High Flow CAT or with just the RH?
Would it still be Emissions legal without the CAT? Hmmmm.
I'm not looking for mad performance. I really just want to get he engine to breath better for now and I hate the look of all these Mufflers. Just want a fat straight pipe sticking out the rear.
Any experience with the sounds these set ups produce?
 

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Engineering
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Are you in Orange Co. California?
I need to pay attention to Ca. Emissions Laws.
What type of Res. should I get? (Wool filled, glass filled, etc)
What about the stock CAT, is it 2.0" If I go with a 2.5 INlet/Outlet will I need to stay away from flow through to keep my emissions legal? Also, what type of gasketing is best?
So Let me see if I have this right.... RH (2.5 I/O) - CAT (2.5 I/O) - Res. (2.5 I/O) - 2.5 Straight pipe (maybe with Tip). Do they have pipe stock that has a bigger tip than 2.5 on the outlet end? Maybe 3-4" ?
Also, I don't have a whole lot of acess to a shop. Are all of these pieces available with 2.5" flanges?
Just trying to wrap my head around this before I move forward.
yeah i'm in CA. you should look to get Magnaflow resonators, best i've seen. stay away from glasspacks, they suck ass. just because you have a freeflowing system does not mean your emissions will be worse. remember, the piping size has nothing to do with emissions, its the cat that has to do with it. so you will still pass emissions if you have your stock cat with 2.5" piping. the exhaust shop should have the right gaskets. you won't be able to run RH with a cat, unless you get the Jackson racing one or Strup, but those take about 5 weeks to order + they have to make it custom spec for you. so i suggest you just get a shorty header. the high flow cat and piping will need flanges welded on. you can find flanges somewhere online, or at the exhaust shop. and you can get 3-4" tips from magnflow as well

Caught with the High Flow CAT or with just the RH?
Would it still be Emissions legal without the CAT? Hmmmm.
I'm not looking for mad performance. I really just want to get he engine to breath better for now and I hate the look of all these Mufflers. Just want a fat straight pipe sticking out the rear.
Any experience with the sounds these set ups produce?
without cat, you wont pass smog.
 

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Caught with the High Flow CAT or with just the RH?
Would it still be Emissions legal without the CAT? Hmmmm.
I'm not looking for mad performance. I really just want to get he engine to breath better for now and I hate the look of all these Mufflers. Just want a fat straight pipe sticking out the rear.
Any experience with the sounds these set ups produce?
no cat in Cali equals huge fines!!
 

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Attitude Adjustment Eng.
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Discussion Starter · #11 ·
Def want a 4-1 RH if Possible. But just leads to more questions.....
Why would the CAT need to be custom for the RSX? I/O differences?
Also, on the other side of the coin, if I reflash does that make a difference in a shorty vs RH? I have been reading that with a reflash and a RH, it runs too lean.
Plus, maybe the shorty with a hight flow CAT and a reflash solves all of my Emissions problems. Right?
Just trying to hash this out.....
 

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Engineering
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some highflow cats i've seen dont come with flanges. that's why i said that earlier. reflash and RH will only make you run too lean if you have an 05-06. yes, your best bet would be shorty-->2.5" ID/ODhigh flow cat-->2.5" ID/OD 22" long resonator-->2.5" straight pipe (with tip if you wanted)
 

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Attitude Adjustment Eng.
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Discussion Starter · #13 ·
shorty-->2.5" ID/ODhigh flow cat-->2.5" ID/OD 22" long resonator-->2.5" straight pipe (with tip if you wanted)
Thanks- What kind of power will I gain from this setup? Would I still want the reflash?
Any expeirience on how this will sound? Don't want it to sound like giving the Tin (Wo)-man a raspberry.

EDIT- Can I still pass smog in Cali?
 

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Engineering
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you will feel a loss in the low rpms, only because you dont have any mods at all, plus you will be running quite large piping. yes you should still either get the reflash or K-Pro. the resonator will quiet it down a bit, but i dont know from experience how it will sound. i think you'd be able to pass smog barely lol
 

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I don't know you
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you need to research headers/race headers. do some searching. here is a general 'guideline.'

race header = replaces exhaust manifold + cat = ILLEGAL (for us in cali and most of the u.s.)
short header = replaces exhaust manifold only
test pipe = straight pipe = replaces cat only
catback exhaust = replaces b pipe + muffler = 'illegal' in cali - will pass smog but you will still get fix it tickets for having a non stock muffler.

pretty much, in cali, replacing ANYTHING with aftermarket will get you a ticket. anything will pass smog except eliminating the cat, that is until it is time for the visual and they tell you you have a non carb exhaust/intake, etc.

as far as performance, unless you will get a race header, dont bother with an exhaust. dont even waste your time with shorty headers. thats my opinion
 

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Attitude Adjustment Eng.
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Discussion Starter · #16 · (Edited)
Well, I plan on installing an intake also. Maybe CAI or ice box.
So this leads me to my next question: What would be the best brands to use for all of this?
If all else fails, I will just keep my old parts handy when smog time comes along.
So, NT, How are you getting by with all this in Cali?
People have to have a way of doing all this....
 

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Engineering
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magnaflow all the way. i'm still running a stock cat so my emissions aren't that bad. haven't had it smogged yet. since my 2.5" megan drift spec has a very small resonator, it is very loud, but i have not been ticketed yet.
 

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Engineering
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toda race header won't pass smog, running a cat after a race header completely ruins the point of the race header, plus there would not be sufficient room as it will scrape when going over bumps.
 

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toda race header won't pass smog, running a cat after a race header completely ruins the point of the race header, plus there would not be sufficient room as it will scrape when going over bumps.
Not true. The long tube design of the race header is what makes the real gains. That's why a Race Header makes more power than a test pipe. Both remove the cat, but the longer tubes give better flow at high RPMs.

By incorporating a high flow cat you will lose a couple of horsepower but not that much. There was a flow test performed in a car magazine (I think it was SCC) a few months back about the differences between cats and no cats. Using a high flow cat only dropped their power like 1% or less versus not using a cat. The stock cat however was much more restrictive.

If you're hitting the cat going over a speed bump, your B-pipe is REALLY going to be in trouble because of the way the pipe has to turn down to get past that bump in the body. As long as the cat is tucked properly there should be plenty of clearance getting over bumps. Do you know of someone who has done this that has a scrapping issue?

The real issue with CA is that RH's do not have CARB approval so they are automatically an illegal part. Shorty headers like the DC sports have an EO number but they provide negligible gains, except when used with a supercharger where short, fat primaries work well. On another CARB note, I've heard of some new CA regulations, either in the works or on the books, where it's illegal to replace your cat before something like 60K or 80K miles and if you're caught doing so would result in fines and other BS.
 
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