Ron, I'll add one thing. Kenny L at Indy Head told me on my 499 engine with their heads that he built while at Mc Candless, I needed to be at 200 degrees on the starting line because if not the engine would be down on power. The heads lost heat to fast and had to build the heat. When first running the car I went 5.50s with engine getting over 200* and hotter. I dropped the temp (at the line with better shrouds and fans) to 160*, not wanting that much temp,and ran 5.70s. Ran it back hot again after he told me this and ran 5.50s. I would say he knows what he's talking about.