You can sace a lil and buy megasquirt to run it.

 

maybe stock vs stock. But once you start modifying things and port/polish the intakes, I know one guy with both s4 and s5 intakes ported / polished and when he swapped them he only made 1-2hp difference on the same engine.

I think vdi is about the same as abs back then. Good idea, but technology and development were on the weak side.