I don't know if anyone on the board races GS450 other then Rich & myself but I wanted to let you know that after years of effort, Wera has at last indexed the GS450 into the F500 class. For years I was stuck racing against much larger bikes in V4 & V5. Not any more.
F500 is composed of quite a few RD400's & RD350's ,yam SR500's, honda 400's, 500's & 550's with a kaw triple 500 every once in a while. You will of course have to meet all other class requirements.(like 18" spoked rims & twin shocks)
V3 is F500's bump up class in which you will find F500 bikes running up a class along with Triumph 750's, BMW 750's along with Yam XS650/750's
Go to wera.com to view the online rule book, It has not been updated to reflect 2005 changes yet but you can see the class rules as far as other running gear. To be F500 legal your GS450 engine must be kept to 500cc or less.
Bob