My Xterra has a 70 MPH limiter, AKA my wallet! Seriously, at probably 10 MPG or less I wouldn't drive the X at 100 MPH even if it were safe to do so!

This topic has been beaten to death a number of times and it always comes down to this. If you want to go fast, get something designed to go fast, join a club or the SCCA, and take it to a track to play once in awhile. Don't be racing your 2 ton, top heavy SUV with 90 MPH rated tires on the highways endangering people's lives. It's not worth the risk and nothing would suck more than going to a "Federal Pound Me In THe Ass Prison" because your ran your SUV into a compact and killed a baby in the back seat.