Slate - I put this off for the same reason. I finally wound up doing 9/16" holes about 10 months ago. The sound at idle is much deeper and throatier, and a general increase in roar over the RPM range with zero noticeable resonance. Overall, I'm very happy with the sound. I'm even considering enlarging the holes to 1" to get just a little more growl out of it.
I don't think there's much chance of getting a lot of resonance or that annoying "coffee can muffler" racket since you're only bypassing one chamber
