There's no way you can get a r32 skyline, pay 85k credits and make it a racecar, the high current detail level of GT won't allow this. The performance customization must perform this "racing modification", you buy a rollcage, also you might be able to change some parts to carbon fiber, remove rear seats, upholstery, sound insulation, exactly as other GT games and in addition it would be funny to paint the cars as racecars, add wings, spoilers, skirts, but in a detailed way, so, I can't see this happening because the racing modification from GT2 just sounds like "magic". GT5 will be focused on showing how complex is a racecar, and how motorsport can be taken as "art".