05M7 - what about going the lightweight route, rather than engine mods? I see you are on a 2014 but keep in mind my comparison here is for the 800 HO motor...
My buddy has an SLP stage 2 kit on a 2010 M8 and that's pretty much it; I have a lightweight 2011 m8 with the only engine mods being the bdx intake and skinz super q can - bunch of weight loss and rotating mass lost from my sled too. Both sleds are dead even and mine is stock - pull and go 100% of the time which I think is what you are looking for...
Just my 2 cents
im already in the proccess the goal is to be as light weight as can within reason, but id also like a few extra ponnies. im coming off 185 horse.
ive already got reapers headlight delete, carbon fiber clutch cover, ti trackshaft coming, evo can, bdx recoil, new lighter racewerx bumper, bdx brake rotor.looking into carbon fiber side pannels
also putting power to the ground with balanced clutches, mds weights, and custom tunned secondary.