Ok, a lot of info here about what path to head down. I'm chasing 340rwkw, keen to keep stock turbo until it s**t itself. Question is, do i go for a e98 tune or a 95/6 tune? What do I need to do differently for either tune? Is it completely tune based? or do I need to do valve springs with a e98 tune?

Currently sourcing parts...
- Injectors (Keen for recommendations)
- Intercooler
- Larger down pipe (do i need this?, will be hollowing out the cat - easier in NZ to get away with it)
- Larger fuel pump (needed?)
- Larger exhaust
- 3" hot/cold piping
- Adjustable actuator (Keen for recommendations)
- Some description of BOV (don't want wank off loud).

That's my list, anything I should change? Don't have a lot of cash to throw at this at once so will be a slow build.

Injectors, dump pipe and cat are the weakest parts in terms of making power. At the level you seek I am pretty sure fuel pump will need an upgrade.

Get 60lb Deka injectors or higher (I think 60lbr's at 95% d/c flow enough for abt 550 hp)

A larger intercooler may be a good investment since you will need quite a bit of boost to hit that level. Might as well get more efficient piping setup- ie relocate filter to battery side while you are at it.

Some good gains to be had out of plenum as well- the BBM wasn't designed for FI.

Dump pipe is probably one of the biggest restrictions. My turbo runs at 11 psi, but the stock dump and cat mean it drops down to 7.5 psi at high rpm. It just chokes up.

Go at least 4 inch dump. You will need it. Big 4 or 5 inch high flow cat.

You will need at least a twin 2.5 system. Some go 3.5 inch, but twin 2.5 has marginally higher cross sectional area.

AS for BoV, try talking to GFB in Sydney- recommended by MCM, and their replacement for the stock diverter valve can be run at any boost levels.

Thanks mate, some great advice

You also need to think of what turbo you want for when it craps out. You should build the system for the turbo you want and dont wait for the factory one to die first as this could stuff up more the turbo could blow chunks through your system and ruin the lot so in the end you have wasted money. So pick the size of turbo and how much boost you want to run. You could also look into water injection.