Thanks for the replies. Just curious of everyone's opinions on this. With the 555 ECM cutting fuel when the revlimiter is reached, Whipple said " do not continually run on the rev limiter, continued abuse of the rev limiter can cause severe engine damage". Especially in my stock piston 496HO setup scenario.

^^^^ great for the reply so THX - and someone else that agrees with what I have said in the beginning of this post and if you search up here, I have said a bunch before.

And actually OEM merc and in all their OEM service manuals for ECM 555 and PCM 555 lists it drops spark hitting the REV limiter.

Yes. Its hot air with fuel vapor. Not liquid fuel. It's hitting the exhaust valve regardless and we are talking milliseconds not immersion of a glowing valve into water.

Whipple raises the rev limit with their programing, Merc's limit is totally fine. BANG ON

Bup, Thanks for the info. Good to get a spot on answer as to what actually happens when the 555 hits the rev limiter.