I have to agree with too old on this one. The stainless marine manifolds are superior.

I've had Gil's, two sets of Lightning (different boats), but if I had to do another one I'd follow Too Old's advice and go with Stainless Marine manifolds.

-Greg

Jeff, I hope everything is OK with your Wife! My thoughts & prayers are with you both! Robbie & Chris

My new 598" NA motor has CMI Sport Tubes and they look and perform awesome. My application is absolutely perfect for these headers which explains why they work so well. I doubt at 6500 RPM if the Stainless Marine Manifolds would work as well as the 32" runner CMI's. If they indeed work better you would see them on drag racing cars!! For performance at 5700 RPM or below headers have less influence than at high RPM's. Throw a blower in there and things get even more complicated. For a blown motor CMI E-tops or Stainless Marine manifolds are a toss up. For high RPM NA motors something with long runners like CMI Split Tubes or Sport Tubes are the way to go. I have never had problems with CMI, and Stellings looks like a very good option as well. My vote is CMI!!

Craig

This is one topic where the Marine Industry appears to be in the "stone age" as far as development goes. Most of the cast aluminum manifolds are nothing more than an old "tri y' design which is one step better than the old "exhaust log". Most dyno comparisons show they are fairly pathetic above 5200-5400. The majority of the "headers" out there by CMI and Stellings are a better attempt at being somewhat sofisticated but are normally still not "equal length" with a 32-34" runner. Folks pay good money to a builder for heads, cams, intakes etc and then dyno with a drag type tuned pipe showing a nice hp reading and then throw on a eye candy system that probably cost them 15-40 hp at 5500+? I just had to throw my .02 out there!

No Question, CMI. Best Product, Great Service!

IMOP!

Bryan

What are the difference in cost between CMI, Stainless and Stellings?? I need to replace the Gil exhaust on my motors. (HP500's)

Thanks Robbie, she is ok, feeling much better, and have been boating the last few weeks, take care, Jeff and Sandy

We Have Twin 1000's Blown And We Have Stellings

Donz Jr Mike

Randy @ Stellings has been super to work with. Quick service, reasonable, dependable and good information.

As far as performance, only dyno's or trial an error can tell you the difference.

Randy, you better read this. Sending a header back to you this week for a flow test. Need some quick turn around buddy.