The engine is 588 ci made 829hp @6600 and768ftlb torque @ 5300 The headers on the dyno were kromer kraft 2 1/4 step headers with 4 inch collector from my drag truck this engine is going into a pulling truck and I was going to have step headers built for it but I got a good buy on a set of headers that are 2 1/4 tube all the way with 4 inch collector. do you think headers will be as good, better, worse, or about same.

Will be really interested in finding out. Guess is not quite as good.

Invest a few bucks and buy a copy of PipeMax software. It will tell you exactly what header to use for any engine. It will also give you a ton of tuning hints for a race motor. One of the best bargains in the business.

BTW - I'm still using 2 inch headers on my 514 engine and it is making more than 900 hp at 7000 rpm. So those 2.250 headers are probably just fine at 6600, maybe even a bit too big.

It is important to match the header tube to the exhaust port size so that is another variable to look at. You didn't say what heads you're using so I can't help you there. What you need to do is calculate the area of the exhaust port at the flange and then see how that compares to the area at the header flange.