[igor@af]

Having acquired sponsorships myself from the following companies:

Vortech
StopTech
XERD
350EVO
KW Suspensions
Yokohama
Street Sports (a local shop)
SR Racing (local racing shop)

I can say that sponsorships are best acquired without a 3rd party such as the company you represent, considering many compaints I have encountered from people that have attempted using services from such companies.

If you want a sponsorship, you must offer something unique (and guaranteed to an extent) to the company which you wish to represent.
No company will offer a 'regular' car guy a sponsorship.
If you are in a position in which an aftermarket company would wish to offer you a sponsorship, then you don't need a 3rd party anyway, they will be interested by your inquiry and by your well-written proposal.