holy crap someone else is alive on this board??? man, i didn't think anyone would ever answer. too late though
i just got an 18" 2 1/4"dia. glasspak and a tip for it which is also packed and is 3 1/2" in diameter inside. i haven't yet had a chance to hang it but look to within the next couple days. i need to get some hanging hardware. i have to get some sort of coupling so i can attach the pak to the exhaust since they are both 2 1/4".