Hi Seb, great car! I have just bought a 3.0 GTV i have similiar plans to you, i currently have a golf VR6 track car but i have reached the limits of chassis tuning on it, so the GTV is eventually going to replace it, much much better engine and much better centre of gravity compared to even a slammed hatch ;p
I have already replaced my front wishbones, track rod ends, drop links and top mounts, and i am about to put new discs, motul rbf600 fluid and pagid RS15s pads on (i have them on my golf, i did over 90 laps of bedford autodrome last month and no fade, its 3.6 miles long!) to upgrade the braking.
In terms of engine tuning, have you heard of AHM motorsport here in the uk? They do a 3.8 forged piston and liner kit for the 3.0 which they claim will increase power to 400hp without
forced induction! The only problem with it is the price, its Ł2500 and you have to buy a 3.2 crank and MOTEC management
Great videos btw