This is mainly to cover insurances, material related fees, some raffles and shuttles. The over-cash goes directly in the cash prize for the fastest team. Plus, you participate to the most bad-ass, rad & fun event out there.
You can either pre-pay directly on Kayak Detail's website or on race day(cash only).
You can pre-register even if you don't have a partner yet. A lot of people show up on race day and find their partner directly on site.