(long-ish post, its been awhile..)
I just ordered left and right boots from MG Cycle, around $32 for the pair, four in stock. Very nice. Interesting, the local guy quoted $99 for one, with none in stock and wasn't sure he was looking at the right part. I'm 0 for 2 with them but will keep trying so support the local guy.
Regardless, I've put about 7k mi. on my 02 LeMans since getting it in April a few months ago. It had popping in and coughing issues the whole time and the left boot was blown off its mounting collar at the head twice.
I over-tightened clamp the second time in an effort to make it stay. Seemed fine for commuting to work and around town.
Then came my big cross-country ride in July. All was fine until we hit record heat in the desert, 122 degrees down on I-10. Unbelievable.
The heat was too much for the left boot, and it tore itself beneath its front clamp. This made the coughing and backfiring much worse. I patched it as well as I could with black RTV silicone, which didn't work very well if at all.
I babied the bike home, checking temp on the cylinder heads with my hand to be sure the left one wasn't a whole lot hotter than the right one due to lean running. It seemed ok. Highway running was fine, low speed stuff was full of pops and backfires. The bike got me 3k miles home without complaining, I just hope I didn't kill it in doing so.
Hopefully fresh boots will solve most if not all of the popping coughing and hiccupps from before. I will let ya'll know. I want to preserve these boots some way some how from cracking in the near future. It also seems wise to have a backup set on the garage shelf wrapped in plastic. Having them should mean I'll never need them. That's how it usually works, doesn't it?
btw, Thanks for all the info everyone has provided. I have benefitted tons from all the knowledge everyone shares here!!!
Erik