[dammitmitchell]

Oh and to aderess the "torque and rear end" issues...

running the STOCK rear end for the turbos (which is typically the R200 series with LSD)
can handle OVER 1000 hp, it's a 200 MM ring gear with some dang good treatment on it.
it's the half shafts that break on occasion..
a area of concern is the neck for the differential, the stock sheetmetal it's mounted to in the cabin can use a thick reinforcing plate welded or just bolted into place on the inside under your rear seats. I also reccomend a energy suspension (or any good poly kit) replacement, it will help stiffen up your rear end.

If you stay with a GM overdrive (R4 usually) or a 5 or 6 speed manual (typically stolen from Camaros) your gas mileage at a 300 plus HP application stays over 20 MPG..
at 480hp and a 700R4 im estimated to be getting 23 mpg (due to a similar almost exact same build) this can be pushed to close to 30 depending on tire size and weight of my right foot.

these cars were meant for chevy small blocks! or big blocks.!


also weight is no longer an issue, your car will not slow down at roughly 3200 lbs "wet" and 4 passengers, stereo, interior matting, a full meal.... foggy day...
only issue known really is... traction...
that's just my two cents. PM me if you would like a reccomendation for some interior liner, dynamat style stuff but the guy LOVES "z" cars and cuts us all a good dicount