My experience from having built and tuned motors with single and dual plugs is that a wider gap DOES improve combustion at low throttle and low rpm. And while widening the gap does induce very minor retard of the spark timing on the order of nano-seconds, the effect is well outside the rhealm of significance for any ignition system with electronic control as it will automatically find the right timing.
The tradeoff to a wider gap however comes at higher throttle. It essentially boils down to whether the ignition system can reliably push a spark through the compressed mixture which is more dense with the higher throttle opening. (Greater mass increases resistance.) The manufacturers set their spark gap specifications based on the expected output of the motor and ignition system. In other words, the exact same motor setup to produce 'x' horsepower efficiently will need a smaller spark gap to produce more power, and can use a larger gap to produce less.
I fully explored this when I had built my 1.6L Isuzu motor to produce close to 400HP. The manufacturers original spark gap specification was for .032", but anything over 220HP or so produced allot of misfires and severly limited output. After dropping the gap to .025", the motor easily produced power throughout the entire range. Doing this degraded idle performance very slightly with a very rare miss occurring, but it was the tradeoff I had to make in the absence of upgrading the spark energy available.
So the question really boils down to how widening the gap affects your acceleration. I say widen it and see what happens. It won't damage your ignition, and probably won't hurt your plugs unless the clearance to the piston is really tight - in which case they will be automatically regapped for you.
Linear Mode
