Since i put my GMPP Performance Cat-Back it seems to take much longer to reach 120mph on highway.
Is it an illusion cause by the loud sound or did we really lose HP at high speed ????

 

Doubt it but its possible.

 

From what I do know about catbacks,if there is gains or losses, the loss will be on the low end torque and better flow for greater gains on the top end

 

lose if you just have a catback,,save some $ for a complete exhaust system

 

When i put my corsa sport on i noticed a difference, and i dont know about having to have a complete exhaust system to net a gain in horsepower. Never heard that one before.

 

Aren't the corsa exhaust systems complete exhaust systems?

 

Thats what I thought too.

 

Corsa is a complete catback system, he's talking about a complete exhaust system, in other words catback + header + cat + pipe in between them.

 

yah but you'll still net a gain from a cat back.

 

Sounds more like placebo effect to me. You definitely wouldn't lose any horsepower as the gmpp catback should flow better than the stock unit. You may lose a smidge low end torque, but from all the dyno-sheets I've seen w/ aftermarket catbacks it doesn't look like you would be able to notice it via butt-dyno.

Of course...there is always the possibility (keep in mind I'm not saying there IS something wrong) of some underlying problem that could very well be hurting the performance of your car if it really feels lagging than normal...but I doubt it has anything to do with the gmpp catback.

 

I can't really imagine a loss really. most likely, you've just not gained anything noticable.

which model have you got?

also. make sure the car is running right. its possible that something was damaged during install.

 

Anyone has notice that the GMPP Performance Cat-Back is smaller than the stock one

 

The car seems faster from 0 to 60 but now on the highway the 4th gear is like the 5th
I've bought the Performance one
Nothing was hurt under the car i watched them carefully

I hope i'm just getting retard on this lack of power

 

FastSS06 has the GMPP catback and you can DEFINITELY feel a low-end loss, no other problems on the car. It just bogs down on the lower end, but there's a definite perceivable increase on the top end to even it out.

 

I think its all in your head, the differance in sound makes your mind think, damn, i should be moving for all the sound this basterd is making. But rairly will you feel an acuall differance.

 

Isnt the GMMP exhaust all 2 1/4 piping ?? Alot of the stock exhaust is 2.5 .

 

I have the GMPP exhaust and I feel the car much better. If you look where the bolts are at in the begining of the cat-back, you'll notice the down pipe size looks like 2.5" and then right before the flange it corks down to 2.25"

I think this is the reason wht GMPP went with a 2.25" exhaust, since your exhaust is only good up to that point. (reason why I went with GMPP). I did weigh the stock exhaust and it clocked in at 31lbs. The GMPP is much lighter than that.

If you want a 2.5" exhaust, then first get the weapon-R header, since those are a true long tube header, you'll have no kinks in the system, just a pure 2.5" system all the way out.