Second push mower chute

I recently overheard a barstool conversation about an old model Snapper push mower a man got for $10 at a garage sale. He said it started and ran like a charm, but unless the grass was perfectly day, it wouldn't feed through the discharge chute. He's handy with a welder, so his plan is to cut another chute on the opposite side of the mower.
One fellow claimed that this would compromise the deck's vacuum making the problem worse. One overly-libated chap said this would cause the mower to rise into the air. Anyone know for sure?