Drilled mid question.

[Joeb88]

I have a 97 merc 2.5 efi. I swapped to a drilled mid. I’m pretty sure this is obvious but my question it this. Do I need to modify the exhaust tube or just leave it out? If left on and intact it would just direct the exhaust down through the gear case. I left mine out and ran the motor on the hose for the first time and had water coming out under the power head. I’m assuming I messed a gasket up. Or there is a flaw in one of the mating surfaces but I figured I would look In To all possibility’s. I wasn’t sure if not having the exhaust tube in would prevent something from sealing correctly. Thanks

[rgsauger]

The exhaust tube, or "can" as we call it, does not have to be there for things to seal up. Take another swipe at your gaskets and torque per manual. Have fun!

[tlwjkw]

ya got something outta whack if it leaks... drilled (in normal places) exhaust is useless with a "can" in it.............

[Joeb88]

that's what i figured . thanks

[HighVoltage]

I have a 2001 280hp EFI Merc. with drilled mid section and also a Bobs Machine exhaust housing installed on the mid. So you guys are telling me I can run the motor without the exhaust can. What is the benefit of no can. Also why is Bobs Machine selling exhaust tuners if they are not needed.

[rgsauger]

Hang on...a tuner and a can are too different things. A tuner bolts to your adaptor plate. the right one doesn't help much but the wrong one will hurt performance.

A can is the inner cast aluminum liner in your mid that just drops in. It quiets things down and in theory keeps some exhaust heat off of the water pump. Sounds a lot better yanked even if you don't drill anything. Honestly does nothing for performance to leave in or pull out. I yanked mine and it sounds a lot "throatier". Not so much "louder" but definitely meaner.