2 years ago when the car was designed I dont think there was such a thing as a 17.5. Like I said, with any motor but a 17.5 minimal modifications are needed to the gear where you need it to be. I can get down to 3.8 on my car. If you run 17.5 it looks like a prs adapter and a 104-108 spur you can probably get down to 3.3 or something. Thats gotta be close? What do guys run for gear ratio with a 17.5?