Speed increase claims that is. I have seen claims from retailers in Powerboat mag that a swap to CMIs will get you anywhere from 2 to 7 mph. The latest claim being in the Feb '10 issue stating that the owner of a 26 Baja Outlaw can expect 4-7 mph with just the headers and a prop change. That is not going to happen! I fell for this ploy and dropped $4,600 for a set of CMIs to put on my 496 HO in my 2005 Donzi 22 Classic. I saw ZERO top speed increase! I have seen dyno results on paper but I have also seen others post that they too saw NO speed increase. Maybe we can get folks who upgraded their 496 HOs w/CMIs to post their actual results (or lack of results).
Remember, actual results, not paper results.