In Australia there was one name linked with the WR500 - Rob Twyerold.
Super fast and well set up by Rob himself.
Robbie was more linked to making the YZ490 go like shit against water cooled competition, he could also do the same thing with Rotax ATKs so very good mechanic and rider.
Given that it was sold as an enduro bike I made the mistake of using one as an enduro bike, Robbie did the barrel and head and I ran pro circuit pipe, but it was still a pile of shit when you rode it next to almost anything else at the time, that motor was all mid range and in sand whoops and tight stuff the power was just too narrow, YZ490S was better...... but WR had good chassis and probably good trail/play bike but against for example a KTM 520 or open class enduro it was a dog. I rode it back to back on a loop with Mark Whites 520 and promptly chopped it on WR250 which was an awesome bike.