Its a long time since I came across EXUP !
I had an RD350LC which got rebuilt several times and on the last time had EXUP fitted to add a little (more) extra zing. It was great from a geek point of view. Then again it had a power rev-range of about 3000 rpm so needed a lot of gear shifting.
I had a 350LC YPVS for a while, manic little bike. I replaced it with a derestricted Yamaha FZR1000 EXUP. which was absolutely f***ing mental. Then I realised I wanted to live, so I sold it
