100LL fuel limits the engine to 55" on takeoff to prevent detonation. The
current owners today (non-racers) seldom get above 400 mph. Most of them seldom
do aerobatics and thus likely never get above 350 mph. The commonly know speed
limit is still at 500mph. There are about 120 airframes flying in the US, with
about 300+ still in existance worldwide. Cruise is flown at 35" which produces
220kts/240mph approximately......depending on ambient, bomb rack installed,
antennas, etc. That's about 55% power. Like John said, it needs speed to get
over the top of a loop, otherwise it can stall and depart.
VL