1988 Yamaha 30 Exhaust Ports

[scout-j-m]

I have a newly acquired 1988 Yamaha 30 3 cylinder. It had a bad lower unit at the time of purchase. I bought a used lower last week and changed the old but clean oil and put on a new impeller. It’s pumping water fine and shifting good. But one thing I noticed is that the two slit exhaust openings above the cav plate looked to be painted over. I took a drill bit to them to clear them out and it turns out it’s aluminum not paint. Not sure why that would be. They are both open on my the bad lower that came with the motor. Thoughts? Should I drill and file them out to fully open?

 

[scout-j-m]

 

[scout-j-m]

I'm going to go forward with drilling them out. I just can't see any reason for them to be sealed off like that.