The opinion with the Subau crew is that the MXs seem to have really soft sidewalls so depending on the weight of the vehicle this may or may not be an issue for autocross use.

I'm looking for new tires for my car and I'm stuck between the Azenis and the MXs myself. I'm leaning a bit more towards the MXs but I'm still undecided.

Your other options are going to be alot more money.