For max E.T. and MPH I'd definitely do the auto trans. For the max street driving fun factor I'd do the manual (though I'd speculate your ride could be up to a full second slower with the manual trans if you figure a 1/4 to 1/2 second loss per shift average). Unless you're running a Lenco, or you are the power shifter from hell, no human can shift as fast as an auto trans while continuously applying power to the rear wheels, not to mention the torque multiplication factor of a nice converter. Actually it's real simple in my book, as you're running a twin turbo setup = definitely go with the auto to keep the whistlers boosting continuously and smoothly vs pounding your blow off valves to death with the manual.
There is always merit to putting an engine just about up against its rev limiter and side stepping the clutch though!
Steevo's Shrifter will help keep both hands on the wheel during your banzai blasts, which in a serious power situation is always a good thing!
