If you bought the rb25 compressor you would have to machine your housing($50) The VG30 comp and housing would totally bolt on but make 10kw or so less. You will pick up between 20kw - 50kw depending on your tuning, mods and boost. I have made 225rwkw with the RB25 compressor. Depending on the A/R exhaust housing difference between your current turbo and an RB25 turbo you could estimate lag and power differences.
Any of these wheels will make give you a large power increase.