http://www.speedtv.com/feedback/
Also, you can become a member of insider.speedtv.com and message users SpeedTV and Speed1. Speed1 is Jim Liberatore, the president of Speed TV. He often posts on the forum, and replies to PMs as well.
This may or may not be the correct mail address:
Speed Channel, Inc.,
10000 Santa Monica Boulevard,
Los Angeles, California 90067