Stock Exhaust Pipe Size? (And a question)

[Fred931]

What is it? I don't have a dial caliper anywhere and it's somewhere between 2" and 2.5" before it splits at the back, and probably 2" after.

I'm getting rid of the stock mufflers and probably getting a CB glasspack. The question: can I put it before the split and replace the originals with pipe, or should I get two and put them on where the originals are to be removed. Thanks.

EDIT: Thinking now that I will do the entire catback and maybe a high-flow cat. Is there one good catback set out there? I read about some sort of group buy somewhere but obviously that's too much of a stretch.