The tranny has been proven to 7.7 at 196 mph with a Ford 8.8 rearend. The tranny is the only thing in the car that doesn't break (knock on wood). The transfer case is the weak point, not the tranny.

Nicks Evo has a larger output shaft and larger yoke than my DSM....that's not the problem though. The problem was the weld on the yoke of my particular driveshaft. I never broker a stock driveshaft. It wasn't until I "upgraded" to this othe driveshaft that I started having problems.
I've cut plently of 1.50 60 ft's with my current setup and on a stock driveshaft. I've been trying to get it down in the 1.3's where it belongs. I've done alot of 2 step changes, loaded the car less, loaded the car more, stiffened the suspension, softened the suspension, etc....If you've ever seen me at the track (and not break on the first pass) you would have seen that sometimes the car bogs, and then sometimes its spins too much. That's me trying to find the sweet spot. My car really should be cutting better 60 fts than 1.5's. I really can't explain why I haven't been able to do it yet. I've actually cut 1.4's on my old seteup from 3 yrs ago, but it was an easier beast to harness at that time. It will come together. Like you stated, I'm going to try and turn the boost down even more out of the hole.

The 8.8 rearends are available in 3.55 gear ratios....so over running the front diff isn't an issue.

My plan is to upgrade the transfer case to a unit that has a larger output shaft that accepts a larger yoke, and possibly change the rearend. Those are the 2 weak points on the car right now.