Originally Posted by shiv@vishnu
There really is no "correct A/F ratio". But rather a correct one based upon supporting mods/conditions. In the case of the Procede/PWM meth combo, the operating conditions change dramatically: Intake air temps drop 40-50F and effective octane jumps to 100+. So targetting a slightly leaner AFR is perfectly safe and desirable. It's also worth mentioning that dropping AFR targets down to ~12:1 only reduces power by 6-7hp. Most of the power gains come from the IAT drop and substantial ignition timing bump.
as long as it's a safe tune, then it's all