I'm quite happy with it. I put it on the car on the wednesday night, and noticed an improvement straight away. I wouldn't say it adds any appreciable lag, but others say it does. In my case though on the Saturday I had an XForce 3" exhaust fitted and I felt that it went backwards slightly. It may be that the exhaust took away some of the lag perhaps, but it juts didn't kick you in the pants as much when it came on boost. None of this was dyno proven however. So I never really got to drive it much with just the intercooler and no other changes.