Re: High end speed
A regular SRT6 has a limiter at 255 km/h, 5,300 rpm. I know one who has removed the limiter and chipped his STR6 (~356 HP). Best result he got was 280 km/h+ at 6,000 rpm- (Autobahn was not completely free).
My highest I reach with the limited is 245 km/h. There is not much more above this speed. I guess the MT might get some km/h more than the AT.
But personally I prefer the speed between 190-230 km/h much more! The AT often runs in the 4th gear, the exhaust does a great sound and you can still feel the power.
255 km/h = 158 mph
280 km/h = 174 mph
245 km/h = 152 mph
190-230 km/h = 118-143 mph