My ER-6N exhaust.

This hole that caused my Kawasaki ER-6N 09' exhaust sound different from any standard ER-6 exhaust. I guessed previous owner did this. It's not too loud like aftermarket one but I like it. I wonder whether this is going to have effect to the bike performance or anything on long term. Maybe one day I'll fix it or weld those hole but in mean the time I'll just leave it as it does and hopes nothing bad happen.