I was thinking about going to a bigger throttlebody for my for my 99 gsr. How much of a difference would I feel with a bigger one( say 68mm)? Would there be any problems like gas consumption, high idling. Also would I be bettr off having one recieve a bore job or aftermarket one?

 

If nothing else is done to your engine, it will make a minimal difference at best. The throttle body is typically one of the last things that you upgrade. A larger throttle body should not affect gas mileage (provided that you are not driving like a nut) or the idle.

I bored my GSR TB to 62 mm, which matches the intake manifold bore.