I ran 16/38 at Bonneville and probably could not have pulled anything taller. However, Bonneville eats HP due to the 4500ft. altitude and drag due to the salt, so on pavement, 16/36 or slightly taller probably would have worked. I have 16, 17 & 18 front sprockets if you need them, but no rears to spare. Your engine may be peakier than mine depending on porting and chamber design, in which case you may have trouble pulling the 4th to 5th shift. It's possible you'll need to run 1st thru 4th, in which case you may need the 18.