I've had that track for a couple years. I love it, and yes I did loose a little top end. Probably around 5 or 6 mph on my Rx-1, then I put it on my viper and now that it has pipes and ported cyls, i run about the same MPH but way quicker gettting there. I was rubbing on the protectors and I relieved the track to not, but I think at top speed it still rubs. I also have 192 studs and plastic backers, so that adds a little weight.