Jerry Hall recently finished a batch of pipes.  He may have some left.  Arent cheap though.  But you wont find a better performing pipe for a 500.

He personal messaged me!! I asked him about getting one of those new batch Hall HPR19 pipes and a silencer, hope I can get one  
After reading through multiple forums, the Hall pipe would be my best use of $$. Super stoked to get one, it will be in a works finish! Will be a nice upgrade for my new 1987 zilla that I was finally able to afford and find, just happened to pop up about an hour away from me and right when it hit the market I scooped her up! He wanted 2500, but I ended up talking him down to 2000 flat, looks to be in great condition too, only issues I have found is a jb weld tact on the clutch cover (already bought a 87 polished clutch cover on ebay for only $100) and it has a missing front bumper that looks to have been broken off in a crash because there looks to be that the original front bumper screws were broken off and are still sitting in the treads. Other than that and the chain guard being broken off on the motor case mounts, she runs great! Have some Elka shocks on the way too!