power management via timing retard and engine parts

On a methanol fed either blown or turbo combination, how effective is using timing retard as a means of power management to control wheel speed. Is using timing retard hard on cylinder heads, head gasket and the exhaust valve?

 

Timing retard can be hard on the exhaust valve as the combustion event happens later in the cycle and is burning going out the exhaust, which gives false high EGT's as well. I haven't experienced any head or gasket issues by just retarding the timing. It could be more critical on a turbo car as the exhaust energy is what is making you boost.