Best motoring reviewed it both on track and 1/4 mile tests against evo VIII and STI's. Over the VIII the IX was only slightly quicker on the 1/4 but the mid range torque test show a slightly larger improvement. On the track they said that they were unsure of the enhancements made to the AYC and ACD, the back end seemed to swing/jut out unnarturally but they didnt comment any further than that.