[Dominik]

Under breaking you are not achieving the desired numbers, but are the tires already locking up? 1g decel sounds quite decent for a threaded tire, but I am not familiar with latest (threaded) tire capabilities.

I shall dig out the acceleration / coast down test I did in 1995 with a 496 cui and hardtop. Your values remind me of that time. My max rpm was 6500.

Good luck with your V belt! My fan belt also turned inside out. I changed belts and location of the alternator and it seemd to help - for whatever reason.