When you have that much power already (800bhp) the only thing that will really help is reducing weight and getting the best tyre setup you can. Tweaking with the race suspension would also help.
You can add real useable power to weight advantage by lightening for less than the power upgrades, and on a car that is already too powerfull for it's tyres, that is the best option in my opinion. Get more speed for less weight, not less grip for more power!
Dave