Mike85220

http://www.gmhightechperformance.com.../photo_16.html

This dyno test gave the GMPP exhaust a rating of a little over 1hp and 1lbs of torque.
For $600+, forget it...

My wife's custom exhaust with turbo muffler is all 2.25" and her 03 Sunfire loves it.
What is with this GMPP exhaust?
Did they stuff kittens in the cat?

Anyways, I am amazed that the GMPP intake actually gave close to 7hp, someone posted it gave only 2hp. So many variations on results from so many sources... who to believe???

YzRider452

The problem with our cars is that they can suck enough air in. You need more power adding mods so the supporting mods such as cat back exhaust actually do anything.

Jimmys2007CobaltSS/C

iTrader: (1)

on a supercharged cobalt ss its dyno 12whp

I want the tourning but not pay 600 bills for it

Gestapo007

iTrader: (2)

Gmpp Intake Ftw!!

Mike85220

What is the size of the stock exhaust?
What is the size of the GMPP exhaust?

an0malous

why does this crap article keep getting dragged up
*snore*

on a 2.2 exhaust is mostly an asthetic mod anyway.
your not fighting enough restriction to get much gain from it. so just buy the one that sounds nice, and is a bit better free flowing.

stop worrying about +/- 5hp, on dynos that have error factors of 15hp

YzRider452

After i installed my nitrous, i was running the Lsj downpipe and catback. I couldnt run anything better than 14.4, I installed my ZZP header/dp and corsa catback, 13.8. The more power your pushing the more mods like this will help you.

Mike85220

What is strange is that a custom 2.25" exhaust on my wife's Sunfire without any other mods made a big difference in up and go.

It definitely was not a 1hp gain, but I am hearing that these dynos have a margin of error that can make the numbers look pretty weak in the gains. Most likely it is depending on where you go and I assume it is from the condition of said dyno.

GM says their exhaust is a 12hp gain, I am guessing it is more like 8hp if it is the only mod and 12hp if you have all other mods such as nitrous, intake, cam, and so on.

If this was only 1hp with multiple dynos to support the number, I would see this exhaust as a rip-off. But like you said, it will support more mods, but even so... 1hp...that blows.

That is why I asked for the stock vs GMPP exhaust's pipe size.

I am going with the dyno used was not accurate, or they did not reset the computer.

No way it gained only 1hp, not if it went from 1 7/8" to 2 1/4".

I would believe it if it went from 2 1/4 non-mandrel to 2 1/4 mandrel bent. Or possibly 1 7/8" to 2", or something along those lines.

rnjmur

Yeah, on a 2.4L motor you probably won't see much of a gain on a mostly stock motor. You only gain hp from exhaust if the previous exhaust was restricting airflow. On a stock SS/SC I think the GMPP exhaust was gain of like 8hp 6 tq and on a stage 2 it was 12hp and 10tq.

04redline0124

i am selling my gmpp performance catback...200 plus ur stock exhaust LETS DEAL

https://www.cobaltss.net/forums/parts-66/complete-part-out-feelers-138398/

Sbaxtermen

Yup exactly. All the dyno stuff has been said 10,024,353,756,565 times already, but people still don't get it

mkulrey13

iTrader: (39)

jonel the owner of the site has dyno sheet of his 12whp gain from the GMPP ehaust. LSJ mind you.

Sentry

You're going to get a gain, but don't expect it to feel a noticeable difference.

If you can feel a difference of about 5-7 hp, then you must be really concentrating, because it's sometimes a negligible amount. Without nitrous or some other kind of power adder, you can't expect to see significant gains.

YSUsteven

If you look at the results, it kinda makes sense. There was a drastic change in humidity, which may have affected the result.

Also, the results show that helping the engine exhale did not help much. You have to be able to get the air in and out efficiently to make power, and that is why after the intake was installed, it showed a much more significant gain.

Looks to me like the results are valid, you just need to not just look at the number. Numbers are all relative anyway.

Gestapo007

iTrader: (2)

i just cant see spending 600 on 5-10 HP when u can just save some money for a custom turbo setup for like 1500 and like 100 hp. I mean an exhaust is like a common must have mod, but i just wish it wasnt so pricey. Now that i think about it...u kinda need a new exhaust to turbo right?

Sentry

Correct, and that's where you're going to see that exhaust pay for itself.

Try running a turbo setup on the stock 2.2 exhaust, and then open it up to the 3".

To put it plain and simple, none of us are going to see much of any gain because we're not producing enough power. Put an exhaust system on a V8 and you're going to gain gobs of power because it really lets the engine breathe, but the NA ecotec 4 cylinder isn't making as much exhaust, and there's nothing to gain by throwing on a huge exhaust.

rukkee

iTrader: (3)

If you are stock or close to stock a catback is a sound only mod imho.

Jackalope

The problem is the manifold on the 2.2 is so restrictive that what ever you do down stream means ****! You NEED a header or at the very least a manifold off a 2.4 or 2.0 ss car to make ANY difference at all.

ChriSS/SC

The sound itself of the GMPP is worth it.