those are 2 questions I really cant answer.. as i have not personally messed with a 8.3.. but there are a few people on here that have.. and at the haspin rally a got to ride in one that had been turned up to 350.. it was very "peppy" to say the least.. plus he was claiming 14mpg..JD, what's needed to get that much more power out of the 8.3?
Also, at what point is the transfer case going to grenade? We already know it can't handle reverse in low range.
as far as the transfer case, low-R has a TON of TQ on it.. I'm not sure the exact numbers, but it is WAAAAAY up there.. (reverse is a very deep reduction) to get enough HP to start crapping out T-case's (in forward gears) your going to have to be dogging to crap out of it..
just remember guys.. these arent race cars! the power is for pulling, not speed..