Finally got to try the new 5-spd today!
The roads here in NH are finally salt-free (well, close enough) after this amazingly long winter. So I just got back from my first cruise after installing the new 5spd Tremec from Keisler.......and wow, that was sweet! As expected, the 0.64 5th gear was awesome on the highway for cruising......even with my 3.90s, 80mph was only 2400rpm. I downshifted to 4th to see what 80 was like in the 4spd Muncie.......3800 rpm!
And 5th isn't the only benefit, it's nice having normally spaced gears instead of the ridiculously close-ratioed M21. I've said it before, but what a poor decision to put a close-ratio trans in a Muscle car like the GTO that has tons of torque on hand.
The trans shifted smooth and the drivetrain was quiet......the only minor issue was some clutch chatter in 1st when letting out the clutch. I'll see if it improves at all after some miles on the new clutch disc (due to the 26 spline input shaft), but if it doesn't, or gets any worse, I may have to look into that.