In my opinion, I think Its the piss poor air box design. I removed the whole assembly yesterday to install the new INJEN cold-air intake system and was amazed at how small the intake tube was, thats mounted up just behind the grill. In my opinion, I think its a intake issue. With the new intake, I have more pull at lower RPMs. Car now pulls good at 1500 vs the 2000 with the stock box, and now most of the hesitation and bucking, while under mild boost is gone. This intake was well worth the money spent. Im going to buy the intercooler piping next. Turbo's like air, and im going to give it as much as I can.