rear caliper stopper pin/ exhaust

Hi I am having problems with my newly purchased 2001 st110 abs. I also own a 95 version and haven't had these problems !

trying to remove rear wheel the caliper stopper pin was nice and easy to get started but when almost fully unscrewed is just turning in the swing arm boss and apparently is stuck/ stripped on the last thread or two. I tried gentle and then not so gentle hammering from the other side using a drift but is is definitely caught on something. the caliper can be moved slightly on the pin and the wheel spindle has been slackened. I have seen pictures of the bolt on here so I know that with half an inch of thread exposed it must be nearly out. Any ideas what to do. Worst case I am going to have to drop the swing arm but I hope I can avoid this and will have to take the disc off to get the wheel out since I can't get the caliper off the pin. not an enticing prospect.

the .other problem i am having is separating the stock muffler from the collector box. All bolts and clamps are off, I have partially bent back the ears on the the collector side, tried a pipe wrench to rotate rather than pull and it seems really solid. Have drenched the joint in penetrating oil and acf 50 so will have another go after a nights soak.
Not a good start with my new bike which incidentally has only got 16k miles on it and looks as if it has been mainly summer use.
All and any advice appreciated - this is not how today was supposed to go !
cheers
David

good news all sorted. the exhaust came off after the acf 50 soaking and an almighty heave with the stilsons to break the seal. this meant i could get a better look at the stopper bolt and i realised it was fully uncrewed but still very hard to rotate let alone extract. At this point on my other st1100 I could just pull out the bolt with my fingers. this one could not even be drifted out from the other side. With liberal spaying of penetrating oil I managed to pull rotate it out using my mole grips. Very stiff indeed but no obvious reason just a light marking where it goes out of the swingarm. almost as if it it was bent. Anyway new stopper bolt on order and from now on its going to be liberally treated with copperslip.
So for any future readers don't assume that if your stopper bolt is unscrewed you can just reach down between the exhaust and flip it out with fingers.( although you can if its been greased properly). World strongest man wouldn't have managed mine ( 40 lbft just to rotate when fully unscrewed)

I've been trained to avoid that issue by keeping that stop bolt well maintained, taking it out for cleaning and conserving lubrication whenever rear wheel and/or rear brake is removed.
To ease that process I always loosen the LHS silencer to rotate it downward in its collector box pipe (I do not pull it out, this will damage the graphite gasket/bushing), which makes the stop bolt fully accessible by 3/8" ratchet, actually removable, since the can would be in the way, and reachable for a torque wrench when inserting it again.
For this I also keep the exhaust clamps well covered with copper spray, holding off corrosion on them bolts as good as possible.

Why are you guys removing the silencer?

I usually use a racheting wrench to loosen/tighten the stopper bolt . Are you sure you had it totally unthreaded? I think Honda wants you to replace that stopper bolt every time. The new one has thread locking compound on it. I lubricated mine one time and it's worked fine for many brake pad changes.