I would if the 5 was my primary car. I already have my truck and the S2000, so I doubt I'll ever turbo the 5... maybe I/H/E one day. We'll see. I was actually thinking of grabbing a shell and converting it to RWD. There's enough room.
He has a flashable setup from a tuner in New Braunfels close my in-laws' place. There's a lot of drama surrounding that company... at one point I was on the hook to leave the 5 with them for a week to hack the ECU and develop a tuning solution for the 1st gen 5 (Mac has the 2nd gen), but so far it's taken several months and multiple trips with a guy down in San Antonio. I'm glad I didn't leave the car with them.