Drilling Holes In Mufflers

I drilled holes in several places in my brand new TTI exhaust pipes and Dynomaxers, back in 1999.At every low spot. No rust anywhere yet. Cant say the same for the collectors. They've been patched several times, and need some more weld globbed on. I think I'll just buy new collectors.
The holes in the mufflers are a little larger than normal so that water condensing in those big cans will actually drip out. Water has a pretty good surface tension, and doesnt always run through a small hole.
Its impossible to hear them leak with 3 inch pipes all the way out the back.You can see the piddle on a cool or damp day tho.