I run 18" simply because the tires and wheels are cheaper and the sidewall is more compliant on an 18" tire. Next time I will get the 305/45-18 vs the 305/35-18 I have now because of the height difference. The transmission sometimes gets confused because the wheel speed is different than the indicated speed and I don't have a tune to compensate for the tire swap.
#917 A6. firstname.lastname@example.org 1.53 60' ATI/Lingenfelter balancer (10" ring), stock upper pulley, 90mm TB, ID850s,Rotofab/Lingenfelter intercooler reservoir, Cooler Logic HX, Lingenfelter idler relocation bracket, NGK TR7ix, 160 t-stat, Dewitts Radiator, Texas Speed 1 7/8" headers(no cats). M&H drag radials 325/45-17 & M&H 28x4.5" bias skinnies. Tuning by Frost at Performance Autosport in Richmond, VA (804) 358-2505