Boarder line octane and lean conditions at the top of the range, at your shift points, you can warp those run of the mill stainless exhaust valves in no time. When you first get it going you start out with your carb's out of the box Baseline ...unless you'd already had the combo going before and tuned it from there. You fiddle with the power-valve rating ,Shooters , primary ...secondary...generally we usually leave the secondary alone and do most of the work in the primary but once you start getting into high flowing heads High cylinder pressure and big RPM aaaaand you're using a smaller Street carb ....say a 750, you'll find that you are increasing the secondary Jets eventually with the increased volumetric efficiency with all those 'upgrades'.
More power, more heat, touchier on available octane...things happen.
