My first word of advice would be to go to golfmk5.com and go to the australian section.....Massive amounts of info and parts in for sale section. I used to go there when i had a mk5 GTI.
But anything that will fit on the mk6 gti will fit the mk5 gti. Same suspension and brakes. Engine is the tfsi with k03. Intake get a forge twin take!! Rear sway bar....whiteline-local and work really well. Take the brakes off your r32 lol and fit to the gti. Exhaust mmmm so many options for a dump. buy one second hand.
hope this helps