I just installed the FMS Performance Pack (cold air kit / mufflers / X-pipe / short throw shifter / Pro-cal upgrade on the computer), and other than being a little louder, the car actually seems a little slower, like it gave up a little on the bottom for a little gain on the top. Does this sound right? I didn't expect to break into the 8's with this, but I did expect a little kick in the seat of the pants!!! '08 GT, stock except as described, 3.31 gears. Any comments / questions / suggestions?