Fiberglass Exhaust on FIRE!!!!!

I knew my exhausts were in pretty bad shape. They've had little holes in them that I've tried to patch, and they feel weak enough to crush in my hands. Well, this weekend they started smoking A LOT, and it's like they're going to catch on fire... They're obviously due to be replaced, and I plan to do so but I have a few questions about this...

How are they getting so hot, to smoke like that??? Isn't the exhaust going thru them basically smoky water??

Do you think they could smoke that much??? When the smoke is coming out, I'm almost 100% that it's the exhaust, it even smells like burning fiberglass, but if no one's ever had this problem... maybe it's my engine smoking... also my exhaust seems very hot to touch, but not exactly fire hot...

And Finally, what should I replace them with?? Fiberglass again? Or is there a different plastic/rubber product I should buy?? Also, where can I get the best price? They're like 3" tubes that angle up at the engine end... I'm guessing you guys will know what I'm talking about.

Thanks,
kal