Exhaust Ideas...

I was thinking of throwing on my hi-flow cat I've had lying around (literally), and when inspection time rolls around next november, I was just going to throw my stock one back on to pass emissions.

Anyway, I was thinking of using a univerisal magnaflow, or maybe even a 60 series flowmaster, but still unsure.

A bit down the road maybe pacesetter headers.

Any suggestions or alterations?


poop delete this, or move it to the 2.4L performance section, I didn't look what forum I was posting in... sorry fellas, little embarassed.

[Fast Eddie]

No need to change cats, a high flow one should meet emissions.

[Spilner521]

yep..just get a OBDII compliant high flow cat like a magnaflow and you'll be just fine on emissions. as for the rest of the exhaust, a header is a good idea and i believe you can pick one up around 150-170, followed by the high flow cat, one long straight thru resonator or 2 shorter ones, and a magnaflow straight thru muffler. it'll sound really nice and flow better than any other exhaust you can get. as for piping diameter, if it were my car, i would personally do 2.5" all the way back as i've seen dyno sheets showing it makes more power and torque on a 2.4 than 2.25" thru the whole rpm band, plus you dont loose any low rpm torque like everyone thinks. but a lot of people think 2.25" is better so its up to you.

Hey man, thanks for the advice, I really needed it. I looked up pacesetter headers for the car and they were about $235, within my price range :-p.
Pacesetters catback exhaust for the 2.4L was a bit more pricey though, pushing $300, so I'm not sure if I wanna hop on that yet.



By the way, spilner, did using 2.5" piping show a major gain, if so, how much?

I don't think my hi-flow cat is OBD-II compilant at all, it's pretty much a chrome testpipe. It was an ebay'ed one for $30 from california for my old probe, makes you wonder.

[Spilner521]

Originally posted by 99alero_dude@Jan 4 2006, 03:54 AM
Hey man, thanks for the advice, I really needed it. I looked up pacesetter headers for the car and they were about $235, within my price range :-p.
Pacesetters catback exhaust for the 2.4L was a bit more pricey though, pushing $300, so I'm not sure if I wanna hop on that yet.



By the way, spilner, did using 2.5" piping show a major gain, if so, how much?

I don't think my hi-flow cat is OBD-II compilant at all, it's pretty much a chrome testpipe. It was an ebay'ed one for $30 from california for my old probe, makes you wonder.

Quoted post

i just found the article..its a 2.4 cavalier, same engine as aleros and cavalier exhausts are almost identical to ours..peak gains are as follows (and these are dyno runs, so hp is measured at the wheels):

Stock exhaust: max hp - 127.3 max torque - 136.7
2.25" exhaust: max hp - 132.3 max torque - 142.6
2.5" exhaust: max hp - 134.9 max torque - 146.1

these are just peak gains at red line. there are certain rpms where there is more of a gain also. plus the low rpm torque is not lost with the larger piping. and remember this is stock with a cat-back exhaust. adding a header and high flow cat will increase the power and torque even more.
here's the website: http://www.iperformance.biz/dyno/exhaust01.html

and with your cat....if its a test pipe, its not an actual cat, just a resonator to go in place of the stock one. you can get a magnaflow high flow cat on ebay for $60 or less so i'd check that. i think my 3" magnaflow cat was something like $64 shipped so a 2.5" cat might be less. hope that helps and any more questions feel free to ask...

Spilner you're a damn library to me man. Tomorrow I'm going around to local muffler shops asking how much replacing my exhaust with 2.5' would run me on installation, but I think I may have to stick with 2.25' for now due to budgeting issues. I have settled on purchasing a magnaflow cat conv like you suggested but I think I want to get a flowmaster delta flow 40 series instead of a magnaflow muffler.

But thank you very much for the information, it really helped my decsion, dude. If you ever need tips on 93-97 Probes, hit me up. :-p haha


P.S. - I'm looking at the 43000 series magnaflow cata convs, it's just the large oval one, w/o o2 sensor bung?

[Fast Eddie]

1. A 2.5" EXHAUST WILL COST TQ. I have 2.25 mandrel bent and I can tell that there is noticably less power below 2K RPMs. I don't care what the dyno says, It will affect drivability, (notice your link STARTS at 2100 RPMs) it's not undrivable but TQ will be affected.

2. You can get an OBX SS header on ebay for ~175 shipped. A good OBD cat from summit for <$100. I may still have the part # at home for the catco model. 2.5" WITH the bung.

3. Don't get a pre-bent set up. Just get a custom one in whatever dia. 2.5-2.25" crush bent.

4. If you get a header for a J-body be sure to have them move the bung 180* around the collector for the O2 sensor

5. Let me know what you do about a flex pipe with the header, I'm on my third.

6. The size of the piping should not affect the price of the install by more that a few cents. The bulk of the cost is labor should run a couple hundred from the head to the bumper.

[Oldsman]

when i went to the 2.5 mandle exhaust i noticed a little less torque off the line but nothing really bad.

but if your just doing say an intake tb etc then go with the 2.25 exhaust. 2.5 works better for larger ports, cams, and even FI

[Fast Eddie]

Don't you have a cat back, not full exhaust, including header? If so what header are you running TRS or Bill's? And what did you do for a flex pipe?

[Oldsman]

i just have the cat back but with high flow cat.

trs and kinda a ghetto flex pipe. but it woun't be on there long.

I just threw my car up on a lift lastnight and got a good look at the underside with a buddy of that mine that's real knowledgable with cars and I got a question. How the hell do you fit a 19' Flowmaster between the rear axle and the rear bumper? That's the most f***ed up (I had originally said oddest, but that wasn't good enough to describe it) stock muffler setup I have ever laid eyes on. He was at a loss, so I suggested the crossflow Flowmasters but now that I look at those better, that won't do much of a difference either.

[Oldsman]

the camaro style muffler (single in, dual out, one on each side) work fine and flow just as good.

the stock muffler is screwed up and makes it so you can't just run any muffler.