you guys are right, I think I lost power also with my 05 gsr. The first 200 or sum miles the car was soo fast with three people in the car but now at 1500 it doesn't pull as hard in top end and doesn't have the same punch when I slightly get on the throttle. I checked my all the IC hoses for leaks and tighten down the clamps but I see no improvement. Haven't hooked up my boost gauge yet so I can't really say if my boost is falling off or not.

 

I went through this as well. You're just getting used to the power and the car. When i first got mine it felt rediculous, and with 3 people in the car it was nothing. Now, I notice a big difference with 3 people in the car, and when i have a full tank of gas. My butt dyno is exceptional.