My 528 made 829 @6500. I'm still fighting the cooling problem. It's good for about 20-30 mins. on the road. idling it can sit for 30 mins or so easy. I have a Ron Davis radiator in it (26ins), 2 12in. Spal fans, ,160 degree thermostat mech. waterpump, 5 & 5 1/4in pulleys still Runs warmer than I'd like.