Turbo - get an HKS GT-RS. Around $2.5k new, $1.5k second hand + fitting costs (new will include kit with all components to fit). If you are paying someone to fit, you're looking at around $300 - $500. Should do 270-280rwkw on 18PSI. Boost from 3k or slightly before.
I have an HKS 2535 which is just a little smaller then the GT-RS, and it boosts from around 2.7k, making 250rwkw on 18 PSI.
Supporting mods
- Suspension needs to be up to the task of putting this power down. If you are still running factory 10 year old suspension, you'd be looking at $1.5k - $2k to go for a Sydneykid setup including fitting.
- You may also require a new clutch - $800+ including fitting. (depends on type, $800 would be for basic button type clutch, twin plate etc will obviously cost much more)
I am managing without a Z32 AFM, but you'll need one if you're pushing past 250rwkw. That's another $300 or so.
Re-tune on power FC ~ $200
Then factory in another 25% for other unexpected breakages or expenses. Then consider the risk that you will blow your engine and require a rebuild.