I just parted with an '02 TransAm that was set up as a street/strip car. The car had a 9" with a 4.33 gear. With just a cammed LS1 it ran consistent 12.0s at 116mph with a T56 Magnum and a Spec clutch. I will tell you that to get the best shifts out of these, the investment in a Tick hydraulic cylinder kit is the only way to go. Prior to having one, trying to shift hard full throttle above 6200rpm or so was impossible. The clutch would either hang up or you would be locked out of gear. After the Tick MC upgrade, the clutch would disengage cleanly as high as i cared to rev it (usually around 6700 or so.)
As far as comparable shifting, I previously owned a 1970 Mach 1 with a Toploader, and have driven a Challenger with a 833. The toploader was the easiest to shift hard with the 833 being just slightly a bit more notchy. That being sad, BOTH are still easier than any T56 I've driven and I've been in 5 different cars with them in it.
As far as gearing with the extra overdrive, I ran 28" tires with a 4.33 gear. If given a chance to do it over again, I would've run AT LEAST a 4.56 to fine tune the trap rpm a bit better and still wouldve been putting along on the highway in 6th.
If you're going to drive the car alot, the T56 Mag is a great tranny but it's huge and expensive and needs a little work to make a crisp shifting machine.
