28HopUp

Lance, all of your advice was spot-on, but I wanted to elaborate more on the tire size. So many people talk about changing gears, but most fail to consider how changing the rear tire's diameter affects the final ratio. I am running 4.10's in my N/A 4.0L/auto vert, but my 275/50R17 tires (streets & DR's) have a diameter of 28", compared to the 27" stockers. Those taller tires change my final gearing to roughly 3.95:1. When I tried out a pair of 26.2" Mickey Thompson DR's, that lowered my final gearing to roughly 4.25:1.

To the OP, you will want a pair of sticky tires with 400rwhp, so read up on the best brands and pick the size tire you want (width & diameter), THEN decide on which gear set you should put into a new 8.8" rear.

EDIT: You will want to upgrade your clutch with the turbo. I had a SPEC2 in my N/A coupe, and was very happy. It did chatter (even with a new slave cylinder), but I fixed that by increasing the engine idle speeds slightly with my handheld tuner. Check SPEC's specifications to decide on which one will work at your expected power levels.