So I have access to a 3 axis CNC at my work and I am going to have a 1" thick aluminum spacer made so I can plug in my Innovate Motorsports wide-band O2 and get some real A/F readings to help tune my boat. It's a jet boat and runs wet logs, so obviously i have to keep the sensor dry. However my question is, when i unbolted the snail off the manifold, I noticed the gasket has water jacket slots on the snail side, but not on the manifold side. Are they blocked off on the manifold side for a reason? Because if there is no allowed water flow from the snail to the manifold, then why does the snail even need the gasket with the water jacket cutouts? Seems like they should just both run the block off gasket. Does this make sense or am i missing something here? Reason I'm asking is i need to know if I have to machine the water jacket slots in the spacer or of i can just leave it solid. See pics...thanks!