Speed limits are 85 MPH on some Texas highways but it's nice to be able to brag about the top end even if wind resistance (and handling) would never allow me to get there. It's amazing that I could possibly go that fast with 3:90 gears. And just for reference I spent a little over $1800 to put the 2004R into my '69 Barracuda but I did all the work myself EXCEPT for the tranny overhaul ($900). I don't know of any overdrive system out there that would even come close to $1800!!!! My gas mileage greatly increased on the highway and the noise level (exhaust drone) went way down.