Go to the bank and withdraw some major "whack"! dont forget to rebuild the engine internals also, or when the boost is up and the revs are high, you might just find yourself with a gearshift knob sticking out of your skull! The GT42r, you are looking at paying 7500 Dollars, and you will need fuel rail/injectors/engine management/stronger trans/transfercase etc... Talk about "wack". (isnt there a bank in the usa called WACKovia?) I digress. The GT35R is stout as well. What do you plan on using this car for? Drags?street? etc...
I also hear you need to get rid of your Airconditioning as well with this setup.
My 2c (or in this case: My 2 shillings)

 

Is your HP measured bhp or SAE net? I think the numbers are different, like PAL and NTSC TV stuff.

 

You asked for bhp. BHP=Brake Horsepower. WHP=wheel horsepower.

One would assume the TC's are identical, less AYC.

Horsepower does not have a large bearing on tc life. Launching the car, how hard and how often does.

There is no such thing as wbhp. It is either bhp or whp.

We have high hp/tq Evo's and cars in general because we are good at what we do and there is a multi-billion dollar industry in performance racing and tuning in the U.S.

Plus, Americans get bored easily and need something to do with their time.

 

the car will be used for little street and mostly drag and circuit racing

i belive the way bhp is calculated in the US is different from here, i just dont see how it is even possible to run 350-400whp on stock turbo/internals! maybe im wrong but it would make more sense that the way you calculated hp was different?

 

You would be even more interested to know that you can run stock internals to 550whp with upgraded turbos also.