Backing up this man 100%. Pretty much ANY forced induction setup on the planet requires higher octane fuel. Your owners manual on your X should have about 12 kinds of warnings that tell you to use Premium fuel (atleast 91 octane).

Running less than premium on your S/C is just asking for poor mileage and engine trouble. On S/C models the ECU and the engine are built around the assumption that you're going to put in premium. Premium fuel is meant to combust properly at the higher pressures of a supercharged engine.

Putting in regular fuel means that the gasoline will likely ignite earlier in the compression cycle and cause bad things to happen. Don't use anything less than premium, and your X will be happy.