I like any solution that involves buying a new tool... and beer! Hadn't thought of the tail pipe expander, might try that. Otherwise can take the mess to a muffler shop, that's easy. Yes, Hollander and Nurail both make fittings that will reduce the size, but they're like $15 apiece and I'd have to take frame further apart to get those on... honest, taking 5 hundredths off the pipe w/sandpaper doesn't seem like that big a deal. I can almost get the smaller to run up inside the bigger by angling it and forcing, but given how soft alu is I'm afraid of wanging on it too hard and getting out of round.
Mtn4Runner, are you old enough to remember "we'll fix it at the put-in?"
Trying to avoid that scenario...