I'm replacing the exhaust on s 500EFI's. Some folks tell me "use Stainless Marine, there is no HP decrease, they are bullet proof when flushed after each use and cost much less. Other's say stick with CMI's. What do you all think.

Thanks for the input.

Depends. Blower application SM are great. NA, CMIs may offer a better solution

They are NA

Unless you are turning high RPM, you likely won't see any difference on the GPS. The most difference is in the bling....

Stainless Marine GEN III They will flow as well if not better than the CMI's, and support all the power you want to throw at them in future if you add blowers. Plus, they dont spring leaks.

AGREED Stainless marine Gen3

i have a new set of gen llls. i also have a set of lightning jacketed stainless headers i am trying tp sell. i look at both of them. the stainless marine have monster runners, short and then dump into monster elbows then monster exit tubes that i will run dry. perfect for my new 565 blown 1000hp motor!

my original 502 mpi 415 horse with exits on transom at water line worked best with good scavanging with long individual runners and smaller collector. plus they looked really cool. the longevity of the jacketed stainless headers are great in fresh water. I have known lots that have them and never any problems. they won't work on my 565 and i think the massive cavities on the SM Gen lll would have not worked as well on the lower hp N/A motor that needs all the help it can get from scavaging to improve the flow. just my opinion.
larry