hi mate.mine is 600 for this you will need to be saFE.
1. forged pistons.
2. bottom end refresh shells & oil pump.
3.25/30 turbos, or similar.
4. 660 cc injectors or bigger.
5. decat & full exhaust.
6. aftermarket ecu.
7. cams 260/260 ideally. some say no so up to you.
8.alot of ready cash.
A good fast road set up with in the safe limits of the bottom end would be 525 to 550 hp at the flywheel. This can be achieved using a single set up or twin Turbos. Thier are many debates on here on what is best, but it depends how you are going to use the car. For a fast road and short track work i would suggest using HKS GT-SS twin turbos with exhaust and air filters a set of cams, Ecu, intercooler/oil cooler up grade, twin plate clutch, improved fuel system and all the normal extras. this would give you a set up with very little lag that would pull like a V8 with app 400 lbs/ft torque and 440 to 460 hp at the HUBS ideal for road use and highly practical. Approximatly 85hp loss through gearbox and diffs.
Dependent where you are in the country will realy depend which tuner you visit, most of them have a good reputation.
If you are based down south Abbey Motorsport ( 01883 732331 )are the most experienced, but they also have customers from all over the UK and Europe.