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post #1 of 6 (permalink) Old 06-30-2010, 05:49 PM Thread Starter
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GMPP Cat-back Exhaust Gains

I know there are many threads about the GMPP cat-back. HOWEVER, I don't believe ANYONE has really dynoed their car with the cat-back only. I've searched HIGH and LOW no website (not this nor others) can tell what are the gains.

Then, after hours of searching, I've hit this site: 2007 Chevy Cobalt Exhaust Upgrade - GM High-Tech Performance Magazine

I don't know if everyone read it, but the GMPP performance exhaust was installed on the SS 2.4 the only gains were 1.2HPs??!?!?!? My jaw dropped after looking at their dyno sheet. I understand that maybe perhaps that the 2.4 has a less restrictive exhaust and they have an auto version, but even at that, how much is there to gain from this?!?

This is really disapointing to see, I don't think people's "butt dyno" is very accurate. Sure the exhaust "sounds faster" but I now question it's actualy potential on the 2.2?

If you read on the article, after they drop in the GMPP intake (mine's on the way), they then gained 6.8hp. I assume that's because they already have the exhaust in place, but seriously, almost a grand worth of upgrades for a mere 8 hps? I mean it is a 2.4, but are we going to see better gains than that? It's essentially the same motor, but larger displacement no?

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MODS: GMPP "Performance" cat-back, GMPP intake, GMPP extrude honed header, GMPP ground effects kit, lip spoiler, gen 4 headlights, DC sport strut tower brace, splitter, vortex generators, motegi SP10, Iridium spark plugs, ractive aluminum pedals, white carbon shift knob, shorty antenna, 4300K HID low beams (screw electricals warranty)

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post #2 of 6 (permalink) Old 06-30-2010, 06:25 PM
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you wont get any significant gains just from a cat-back.

you also have to swap the header and downpipe as those are more significant bottlenecks on the exhaust...as to how much gains, I have no clue.

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post #3 of 6 (permalink) Old 06-30-2010, 07:40 PM
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Well I don't know how much I believe it but I've seen a site claiming it's a 12hp gain. I wish I could remember where I saw it though.
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post #4 of 6 (permalink) Old 06-30-2010, 08:00 PM
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Quote:
Originally Posted by blazerlow View Post
Well I don't know how much I believe it but I've seen a site claiming it's a 12hp gain. I wish I could remember where I saw it though.
That's what it says on the CED site.
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post #5 of 6 (permalink) Old 07-01-2010, 07:49 AM Thread Starter
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Quote:
Originally Posted by blazerlow View Post
Well I don't know how much I believe it but I've seen a site claiming it's a 12hp gain. I wish I could remember where I saw it though.
and also here,

http://www.*************/forums/showthread.php?t=32554

but that's on an SS TC (I think). There's no way that a 2.2 would get that kind of gains, but 1.2HP is just rediculous. I mean COMMON!!!! I thought factory performance parts are -- usually -- the best designed for your car....

Geez, I hope I didn't blow 6 bills for 1.2HP.... (or less...)

Anyways, no one seems to really know....



ok seems like YC autoblocks links to other site well it's off the CSS site:

http://www.FILL THE NAME YOU KNOW.net/forums/showthread.php?t=32554

MODS: GMPP "Performance" cat-back, GMPP intake, GMPP extrude honed header, GMPP ground effects kit, lip spoiler, gen 4 headlights, DC sport strut tower brace, splitter, vortex generators, motegi SP10, Iridium spark plugs, ractive aluminum pedals, white carbon shift knob, shorty antenna, 4300K HID low beams (screw electricals warranty)

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post #6 of 6 (permalink) Old 07-01-2010, 07:52 AM
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Yea the site claims 12hp but I think they're assuming that you have a full exhaust with header and downpipe.
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