There are several neat options for the '08+ WRXs, aside from the SMY Bezel Cluster and DIY A-pillers. Have you seen this? Windshield Pod
I would consider the repercussions of putting a gauge cluster over the piller airbag. If it isn't disabled, and it activates, instead of protecting your head it will be shotgunning electronic bits at your face. If I was you, I'd look at some of the safer alternatives out there. Lots of options that work well and look great.