Looking at a boat with 500efi's that have been rebuilt and have Hardin Marine 500 EFI Flame Arrestor Upgrade Kits. The tubes running from the thermostat housing to the headers have been plugged. Owner doesn't know why and I am having a hard time finding any information on why it would be done. Benefits/drawbacks? Purpose?

so there plugged at both ends ? or the T stat doesnt have the ports

Heading down this afternoon to review and water test. This is from the pictures I have.

I can see the air cleaner being the issue ( over sized ) interfered with the routing of the hoses ?

Hard to tell from the pics but id venture to say the flame aresstors are so big that they were hitting the "T" fitting at the top of the thermostat and it was removed to make room...but in doing that they had to plug the hoses off that were going to the headers. I find that strange cause if memory serves me right i thought there was a plug on the front of the housing you could take out to move that "T" fitting to the front and still keep the hose plumbing....unless the one i remember see was drilled and tapped for the "T" after the fact.......hmmm puzzled

I was thinking the same thing on the housing. I'll know more this afternoon. Didn't know why someone would do this.