i have 19s on mine, and htey sit on the hood. if you run 20 your hood wont close. and as far as the master/clutch just move the whole assembly overlike 2 inchs. i took my booster/pedal assembly out, and moved it over, and reinforced the firewall where it bolts to. my booster is a bout an inch form the exhaust manifold.. works great been like that for over 3 years now.. look oat myprofile theres pics there