When I started driving, I thought it was real cool to shut the key off on my I-6 powered FJ40 while driving, turn it back on and BAMM!!! It only took a couple of those to blow the end out of the stock-ish muffler. I had to drive it like that for weeks and after the coolness of the first 15 minutes ran out I was so embarrassed. It sounded like the biggest POS and I'll never forget the stares pulling up to high school in a rusted, multi-colored, oil-burning, one tail light, rear spring-sagging loud POS with my worn out Monster Mudders on rusty white-spoke wheels burnin' a Marlboro Light. Damn, I thought I was cool. Thinking back, it's a wonder I EVER got laid.
My vote is to keep it quiet, or at least a deep, deep subtle rumble.