Okay, you are cruising at 55 mph, because that's what rpm you like (I think that is what you are saying). That's about 2400 rpm with your setup, if you drop to 3.00 gears, you'll be doing about 65 at the same rpm.
The other thing I mention, since you say you are commuting, if your gonna be driving this thing like Phat at 70+ miles per hour in traffic, if you haven't already you should update your front brakes. Those brakes were not meant for repeated stops from 55+ mph.
With the 3.11 first, you should take off fine with a 3.00 rear end. I don't know how much those gears are gonna cost you. For the amount of money, you are gonna have to spend on some gears, you might get an overdrive tranny instead.
I drive 25 miles each way to work in my 52 coupe daily driver with a 235 and a 4.11 rear, only one short stretch where I get above 50, though, and I run about 3000 rpm at 65. I still get 15 mpg or so. I'm swapping to a T5 one of these days, I've got the tranny and a 3.38 rear, just can't bear to work on it on these nice sunny days.
Chris
