Hello all I'm new in the world of Cobalt wonderment . I just recently purchased a 2005 cobalt SS and looking it over I see it has some GM performance parts on it. I was wondering how much difference there is between the GM performance re tune and ZZP options re tune . The GM parts that are on it amount to a 3. inch pulley along with the 42# injectors, I didn't get much chance to actully drive the car after it was delivered the PCM had a internal memory failure. I got a new PCM and got it running. The new PCM was porgramed with stock settings. I am now getting it ready to have a performance re flash and wondering how much difference there is between the GM stage 2 and the ZZP stage 3 in actual performence? Any takes on this? Best Regards

 

you gotta be a bit careful here with what you are doing. you mentioned the car has a gm stage 2 kit on it, that comes with larger injectors and for the car to run correctly it MUST have either the gm stage 2 tune or a custom tune, the original tune for the car will not work. now, if originally the gm stage 2 kit was installed by the dealer, part of installing the kit is reflashing the car with the gm stage 2 tune. when this happens gm's system for reflashing reasigns the proper flash for the vin number, and its not actually possible for any dealership to flash it to the original tune. now if the stage 2 kit was put on by someone else gm would have no record it was done, and the computer thats flashed to stock settings is now wrong for the car.

how would you know? well, how does the car run with the new computer? does it start and run as you would expect, and drive normally, or does it have excess fuel out the exhaust, struggle to idle, have a check engine light, missfire, etc? if it runs just fine you have the gm stage 2 reflash and there is nothing to worry about.

as for gm stage 2 to a zzp stage 2 setup, your not going to gain much. i wouldnt run a smaller pulley than what you already have, so the only real change your making here is a different tune, and its not going to change much. the zzp stage 3 kit adds in a heat exchanger, and while that helps i wouldnt go down from a 3" pulley with just that kit. if your wanting more power i would start with a longtube header and full exhaust. next would be a dual pass intercooler end plate and a 2nd heat exchanger. once you have those things, go with a zzp stage kit with a 2.8" pulley, and if you want a cold air intake do it at this time (being our cars are a mass air flow system the tune is affected by what air intake you have on the car. on a stock/gm s2 flash you generally will get a p0171 lean code from having a cold air intake on the car. if you get a zzp stage kit they will adjust the tune for the air intake your running, so if you want one, best to do it when your getting a tune). doing these mods should put you in the 260-270hp range, gm claims 240hp on a stock car with the gm s2 kit. keep in mind peak numbers arent everything and the mods listed will give good gains everywhere under the curve.

 

Hello thanks for your reply I really appreciate it , Since I posted this I did some research and decided to go with the same mods you mentioned. I am putting long tube headers a down pipe 2.5 inch exhaust larger ZZP stealth heat ex changer dural pass end platte 60 injectors and a 2.9 SC pulley. along with a ZZP 3 inch cool air intake ZZP tuned to car to the above mentioned mods. Before I went to far I did a compression test all across the compression run 185lbs there is 60 k on the car the engine is clean and free of leaks. I just got all the parts and ready to have some FUN! I was wondering if you know any one who has installed ZZP's Stealth heat ex changer?