From the first time I started it up, I could feel the difference. After running it around until it got warmed up, I went to start tuning it. Tuning it was simple. I had a bit of trouble with the pipe staying on (Stinger 360). It may not have been the extra HP doing it though. It did go much faster and it would have pulled great wheelies if the tires would grip. I don't have superb tires on it at the time. Racing another Sport with the same engine (Un-ported) in a 150 Ft. Race, I won with 15 Ft to spare! I suggest this mod. to people who want more from their .15 or Pro.15 and don't have to worry about it blowing after the port job is done. More porting could have been done, had I really grinded into the case, Which i didn't even grind into the case, only the sleeve. This is just my experience with it.