As of yesterday, the number of participants registering to compete for GT5 competition were 9 with 3 more likely to join in.
It is possible the number will keep rising up if registration is allowed on spot.
An update on GT5 competition:
1) It will no longer be a head to head race splitscreen, but rather time attack mode.
2)A random track will be drawn in which each will take turn recording their fastest clean lap in a maximum of 5 laps given.
3) It will be knockout format.