PremierPOWER

Has anyone removed the catalyst manifolds on the newer 6.2L Mercruiser 300/ 350HP engines (NOT the older GM block version)? Have close to 700 hours on my 2018 Monterey cabin cruiser and thinking of replacing them with Stainless Marine/ Hardin Marine/ etc. Curious if anyone has had any success in doing this? I know they make a module that plugs into the O2 sensors once removed.

cheech

I have no experience in the matter.
But does Stainless Marine or Hardin make any exhaust for the NEW 6.2's?
Not much outside info on them but I did read an article where they are a clean sheet design and share a lot of parts with the in house designed Merc 4.5L six cylinder.
I wouldn't doubt they have small block Chevy pattern exhaust but do they?

cheech

Boring day for me. Looked up longblock for the Merc 6.2, doesn't look like they deviated much from the standard smallblock.
Exhaust ports look the same that's for sure.

Otherwise also noticed the catalyst (#5) has its own part number so must be removable.
So if not combatting corrosion and you could get the tuning issues squared away, might just be able to remove the catalyst.

techman

700 hours on the original units? Why not keep it stock? I can't imagine aftermarket exhaust will gain you anything except complexity.