So, if you tried helping me before, thx, but the problem is yet to be solved. Did a bunch of tests, tried a few different things, put it back on the dyno and still have the same loss in HP.

I need HELP guys!!!!

Myself and my tuner are completely stumped.

Here is the most recent outcome via an email to HPtuners via my tuner at SpeedDreams:

Have a 2005 Cobalt ss/sc that's way down on power. Car ran great for months, came in last week and dynoed 50 wheel horsepower less all of a sudden. Vehicle passed compression, leak-down and injector flow testing. Tune is still where I want it on the timing/af.
So far this is what has been tried to fix the problem:
-Exhaust has been upgraded to a lt header and catless 3"
-Spark plugs have been switched for 1 heat range colder plugs
-Supercharger has been verified to produce the same 15.5 psi
-Torque is only off by 10-15 ft. lbs.
-IAT's appear to be within range and heat exchanger is flowing coolant
-Hp curve is significantly affected being 5-19% lower at all rpms

Here is the log from our last try on the dyno recorded on HPTuners:
http://www.turboninjas.com/gallery/d/24191-1/jjrun022_hpl?


Here is the actual dyno results: blue is original 262whp dyno, Red is current:
http://www.turboninjas.com/gallery/d/24194-1/jjdynorun1.jpg

I'm really at a loss here guys. Other than the loss of power the car seems normal. I don't know what to think or where to go from here.....

maybe they had the dyno resistence set wrong....

yeah if you cant notice a loss in power, id guess they had the dyno setup wrong at one point or another. 50HP would be easily noticeable.

262 hp is a lot at the wheels i know a cobalt with 20 psi and hes putin down 265 i think they set the dyno wrong your first pass like he said that would be extremly noticeable