I have a MK2 16v which has 205 bhp and just overb 160lbs of torque....I run it with Dunlop D01J's or Yoko Advans. It weigh's just over 1000kg with seats out on low fuel.....and I use absolutely 100% of it's power pretty much 100% of the time lap after lap at Combe and I manage to pedal it at 1.21-1.22 per lap on a nice warmish day when the tyres are at their optimum.
I have never replicated these times in my Edition running stage 2 power (on my old car) but mainly this is down to two things....brakes and a differential. Even running 330+ bhp means careful management of these power levels.It is crucial to get the full benefit of these power levels adding in these items. Boost out of corners using the diff can be better modulated to maximise traction especially on Inters. I also ran the Edition on Inter's but I only ever managed to get to within 2-3 seconds of my valver. Much of the time lost was also heat soak due to lack of a big I/C and big brakes where you leave braking very late.
I have just brought the MK2 out of hibernation for the summer and will look forward to the summer track season. My view now in hindsight over my old Edition is keep it at stage 1 and with the handling enhancements I may put the big brake kit on but leave it at that for road use only. It is such a big investment that will necessiate a clutch, diff, APR fuel pump, exhaust new mapping, intercooler, VWR intake, runner flap delete etc + labour and this all adds up to £8-9k with the brakes!! It's just not worth it for a 50bhp upgrade....it's dead money on resale and the costs don't add up in my book. In it's current form running 310+ it's good enough.
As Hurdy states going over 300bhp to benefit 4wd going 400bhp you really will notice the difference.....bit like going from standard on an Edition 30 to stage 1 such is the gain.
I may change to an SQ5 and just keep the MK2 as my fun car although if I wanted massive pound per buck I'd take a GTR .