Re: Is the XR6T Mk.2 slower than the Mk.1?
Yeah, I wouldn't be surprised if conan is spot on. It depends a lot on where the peak torque and torque range happens - and remember that it's a very flat torque curve on the XR6T. 450nm from 2000rpm to 4500rpm from memory.
So, you should be able to get away with changing gears in a 5 speed in those bands. The 6 speed will just have another change in there resulting in extra time off the loud pedal for a 6 speed vs a 5 speed.
Six speeds (and 5 for that matter) are mostly useful where you need to keep things wound right up at the hi rev range.
Of course, 'faster' depends on where we're talking. 0 to 60, 0 to 100, qtr mile, top speed run as to how many gear changes you'd need. Or if we're talking about around a track, it can depend on which track. That's why race cars modify all their gearing to suit each circuit...