There's another path, AP's car is very unique and probably the top of ladder, but!

Here they are some options,

C2 Turbo + WMI, done by Beyond Limit Autos in Sydney, MK4 R32
CTS Turbo, none done yet,
TVS SC + WMI, done by Beyond Limit Autos in Sydney, MK5 R32
ABT SC, done by Beyond Limit Autos in Sydney, MK5 R32

TVS kit:





ABT SC



C2 Turbo + WMI MK4 R32



I guess it all depends on how much you want to spend, all of them with extras and install are around 20K+