Why exactly do you want to rev to 8k? Without building the engine and on a boost pressure you're mentioning it should be possible on a standard engine to rev to 7500 and still have power
I'm changing the final drive as well, so based on max speed in each gear, it makes sense to increase rev range and push the power band higher up
So, bit of an update. Had the car on the dyno again yesterday and finalised the tune on 1.6bar, it will stay like this till coming winter when the engine will come out again for a few upgrades
Maybe i need a tubular mani as well LOL! Be interesting to hear how it sounds on the cast manifold with EFR