Wasn't able to go above ~312 mph on P-47 at about 5000 ft. I had WEP on, Throttle, RPM, Turbocharger, Mixture all to the maximum, outlet cowls shut, inlet cowls and oil rad are at about 50%. Do you think Thunderbolt should have reached higher speed?
Reference for P-47D-28 top speed:
Check top speed at standart atmosphere, +15C temperature and 760 mm.hg pressure AGL. In quick mission - on autumn maps.
Airplane - 50% of fuel, 8 guns, standart ammunition. 64 inch MAP, 2700 rpm, auto rich mixture (80% of lever), cowl flaps and oil cooler flaps closed, intercooler flaps - neutral (50%).