In your Live settings, change your Outbound ranges. You can modify them when doing a Custom Challenge too.
"Get matched more quickly by allowing a larger opponent rating range."
I changed my outgoing settings to -200 to +200 and the system is still trying to match me up with someone in the -25 to +25 range. It's taking too long to get a game.
How do I allow a larger rating range? I used to just look for a match and get connected after 10s or less. Now it takes ages