I know this is 3 months old, but any chance you still have this stuff? I'm interested in the weight jackers. Who makes them and how much would you want for them?
If you've already got a midpipe, and it's the proper midpipe and catback for your car, and you're having issues, something's tweaked- either the exhaust or your frame.
Just massage the existing bends in the pipe to give you the clearance you need. It'll be easier and cheaper to do it this...
for sure you'll need a new clutch, flywheel, shifter and bellhousing to go along with the new transmission. I believe you'll also need a new driveshaft, and I'm sure there may be other little odds and ends here and there that would be necessary.