I have factory Gill/ Mercruiser high Performance exhaust manifolds on my HP500 motor. It has the "Captains Call" to switch to quiet mode which I will never use.

I also have a set of the Stainless Marine "High Torque" exhaust manifolds and manifolds and riser set which I bought for another boat but sold the boat before I could install them.

WOULD THERE BE ANY ADVANTAGE IN INSTALLING THE STAINLESS MARINE IN PLACE OF THE FACTORY GILLS?

I HAVE HAD STAINLESS MARINE ON PREVIOUS BOATS AND LOVED THE PERFORMANCE AND SOUND. NOT THAT I DON'T LIKE THE SOUND OF THE GILLS BECAUSE DO. bUT THERE MUST BE SOME BACK PRESSURE WITH THE CAPTAINS CALL SYSTEM.

WHAT DO YOU GUYS THINK.

Stay with the Gils if they are sound, Think about the captains call, you have 2 big openings instead of just one without them. No way there is anymore back pressure. Depending on your risers, if you decide to go to upgrades and go to a cam with more overlap, then the captains call risers may have to go in favor of a riser that is dryer farther back. This will reduce the chance of reversion hurting the motor,

The Stainless Marines will outlast the Gils according to previous posts on another thread. Seems like there are plenty of used Gil risers accompanied with worn out manifolds.

My Gils have been in fresh water all their lives and are vintage 1990. I dont think Id be comfortable running aluminum manifolds in salt water for any period of time.

Sounds like there is no need to change them out to the SM exhaust.
10-15 years on the Gils is a good testament to their durability.
I stand corrected.
Do a search in this section and you can find a couple members with some Gil risers for sale if you want to eliminate the Captain's Call.

Well, If you NEVER use the switchable, get rid of it along with the "Y" pipe. Someone will pay you money for that set-up. Then install the SM equipment, since you already have it. It should be slightly more efficient than the Gill and you won't ever have to worry about salt. --- Jer

my S/M are 11yrs old I run in salt water, but I do flush them out after use. and they make a little more power than the gills.

Aren't the SM and Gils manifolds basically the same design? Longer dividers to keep the side by side firing cyls, 4/6, & 5/7 from pulling from each other? Both same 4" risors. Where's the difference to make more HP one over the other?