Different CMI header types
 

I posed this question on the end of another post and it didn't get too much of a response.

I plan on using my e-tops on my new powerplant, 540 cu in @ 700 hp. What am I leaving on the table? CMI's are very expensive, so I would like to use what I have. They are 4" headers with a 4 1/2" tube exiting the boat. What are other doing with NA power?

Re: Different CMI header types
 

You will probably get lots of different answers on this, but; Generally speaking, unless you want to run over 6000 rpm, it would be my opinion that there would not be much to gain by going to the long tubes over your e-tops. --- Jer

Re: Different CMI header types
 

Thanks for the reply. I would imagine max hp would be around 5,800. I'm certainly not looking to spend money if it isn't going to do me any good! The engine builder didn't seem to think that the gain would offset the price of new headers. Just wanted to get what other views are.

Re: Different CMI header types
 

I appreciate the honesty. I would like to have 750 hp or more, but know that I won't be close. Thank you.

Re: Different CMI header types
 

There's also a small matrix on the CMI website to help you with your decision.


http://www.custommarine.com/headerap...erAppChart.php

Re: Different CMI header types
 

TRICK - great explanation of header types and hp limits. Looks as though I will stay with what I have. I may need some clamp-on mufflers as the tailpipes should go through the transom about 7 inches. I'll know more once I water test the boat and my wife adds her 2 cents!