The problem with big turbo is you lose lots of low down power and if caught out in the wrong gear, can be seriously laggy. That's why Hurdy has been put off, even with a 4WD Golf R
This isnt strictly true with the newer GTx28 setups. Having driven the APR golf extensively for a few weeks at a time with both the K04 STage 2+ and the GTx28 setup, the extra lag is not even notable. Maybe this wouldnt have been the case if it was the older GT28 series setups, but i think the new turbos get past this.
just remember Jeremy testing that 400bhp Evo on Top Gear and getting overtaken by a 1.6 Fiat as the turbo was so laggy.
Having driven an FQ400, i concur it is seriously laggy setup. Even the FQ300 is a laggy engine. The GTx28 spools so much better than those do.
But again, why would you be in the highest gear then decide im going to go WOT at 30mph!!! Its completely irrelevant.
Seriously though, 380-400bhp and a flat power curve like James's would be quicker on the road than some big turbo setups. Remember it's not peak power, it's the power curve and delivery
Having looked at his power curve id be surprised. Its savage low down, hence why he spins his tyres in 4th in the dry. If your able to spin your tyres in 4th the reasons are simply A- Theres too much power B - The power delivery is to aggressive C- The tyres are websters. And this is of course in the dry. Add some moisture on the deck and the car will become pointless, with Mr Fiat Stilo driving away in the distance.
I personally dont think its worth while going above a K04 Stage 2+ output of say 350-360hp on a FWD car. I agree, AWD is needed or BT setups.
Jame's car looks much much more aggressive low down the rev range than the big turbo setups. IMO I would expect a big turbo car with the reduced low down power to be more tractable. Plus the newest revisions of the stage 3 setup fueling now has them running 450hp!!
Plus Id wager Jame's turbo with its WMI setup is working much harder and will be much more highly strung to run the 400hp he has than a GT series turbo will while achieving substantially more power purely as it wil have a lot more headroom.