powerboat

My engine will be outputing approx 500- 550HP I have EMI exhaust manifolds now with the cast aluminum tops. Would I benefit any by switching to CMI Tubular headers or will the HP difference be minimal. Or should I spend 800 and get the stainless risers for the EMI exhaust. Any benefit for longevity with stainless versus aluminum with salt water usage?

dyno

my guess is that yoou will see 30+ hp from the tubulars

DanB

Depends on the cam, and how it works with your runner length. I had EMI on a 510 mild motor and switched to Lightnings.(32" runners)... BIG difference in the mid range..really woke it up. Not much if anything on the top..maybe 2mph.
CMI's have 15 1/4 and 32" runners. Depends on the model. If you dont do too much salt water..I'd look at Lightnings. Havent tried there all stainless. Plus there local to you.
Dan

powerboat

Thanks for the input. Will probably sell my EMI and upgrade to CMI's

bsag

Good choice, Ive owned both of them. Did i forget to mention, Love my CMI'S.