modified firing order big block

I agree 67 - but we have to remember that no induction or exhaust is perfect due to packaging. The benefits from fuel distribution are a small proportion of the increase. The rest coming from the reduction in crank twist and harmonics. We're talking about gains of 1/2 to 1% from it... Not huge figures. I could see where a restricted class might benefit - like the FAST guys, or 2bbl short trackers, etc.