Forget the Z4 and get an Apexi Power FC and get it mapped properly if you fitting a TD05 (Which is a very good turbo for your needs), that is the only way to unleash its real power.
You would also need a 2.5" full decat exhaust and panel filter, but it wont brake 300bhp
To brake 300bhp your gonna need :
- Fuel Pump (walbro)
- Fuel Regualor (SX)
- Parrallel Fuel Mod
- Upgraded Headers/Manifold (Harvey Ported Headers)
- Front Mount Intercooler
- Induction Kit (K&N)
- 440cc Injectors
Hope this helps
Craig