A buddy of mine tried to tackle the exhaust himself, but gave up after a while. Drove it to the exhaust shop some 25 miles away (mostly back roads) with open headers. Uh - let's just say it was a bit loud when he got on the gas! He was setting off car alarms as he passed! Hahaha!
Luckily no police pulled him over. I'm actually trying to think what the ticket would be - probably the same as the "ricers" get with loud exhaust systems. Usually it's a "fix it" ticket where they have to replace their loud muffler and bring proof to court. Luckily for you, you'd be on your way to the exhaust shop anyways, so you might be able to have some fun!
Of course, I'm no lawyer, so I can't exactly say what would happen - plus, with no back pressure, I'm sure you'd be backfiring underneath the car every time you let off the gas. Can't be too safe.
'68 Firebird, 350-4, 2 spd auto, triple black, Dlx Interior