so you would essentially be bolting the subframe directly to the bottom of the car? what would the benefits be of doing this?

It's just to lower the car.

I can get the ride height I want without having to adjust the coil-overs too much which would impact the suspension geometry.

It also lets me lower the car without reducing ground clearance at the engine/trans.

That's what I thought, I'd like to get mine lower too, I may have to check this out!

I run no bushings (on rear of subrame, still need a ~1/2" spacer on the firewall mount due to difference in height) and a stock T56 and cut the whole tunnel out front firewall to rear firewall.. when you already modified your tunnel did you remove the under-floorpan stamped brace that's located between the seats? That was the first thing to hit my trans to my recollection. If you want to do it right you'll want to leave a ~1" gap around the trans for vibration/rotation and adjustment when fine tuning your driveshaft angles. My engine/trans angle is 0.5* down I believe, and I was able to trim the trans tunnel starting at about 3" back from the front firewall.. I was able to all the cutting and welding from inside the car.. I didn't need to cut all the way up to radially outwards on the firewall.