Look at a vf35 instead of a tdo4h. It will c 340 but your gear box will not but with the vf u will be running safe and they are normaly £300-350, exhaust if yours was a prodrive it's cool for 320hp so no need to change Plus u will not have to worry about the mot fail due to high co2s. Pfr7bs £40-50 yes and I would say k&n or cosworth panel filter £30-40 max and Sti top mount should come with y pipe £150 max and a good mapper £300 open source or -500-600 Ecu Tek. Mapper is a big thing. Good luck and as the post above said Breaks and pads. I think just pads