Mercruiser riser gasket question

[acdc96]

Well i took the risers off my engine to clean them and paint them. I noticed that it had restricted gaskets.
What's the deal with the gaskets being restricted flow of water?
I know there are no flow, restricted, & full flow gaskets.

 

[Fun Times]

Re: Mercruiser riser gasket question

The information inside the link below my be able to help give you a better understanding between the 3 gaskets.
Marine Exhaust Systems and Gaskets - How To Tips | Performance Product Technologies