Dunc, it depends on the bikes that are there really, the 04 onwards bikes have more top speed than your bike, the gearing i was running was 15/46, i had other gearing that would have given me more top speed, but the infield section would have suffered, what gearing have you got? Your bike with 15/43 will top out about the same speed as mine was at 153-155 or so.
Don't worry about it though, just enjoy it mate:thumbup