FU(K UPR they steal all there designs from everyone else. Get the Steeda pieces. Trust me these pieces are quality and are exactly what you need. In my opinion any mustang who has a short throw shifter and dosen't have these pieces with it is just foolish.
My vote is for the UPR Extreme. Sure they copy (or steal) other's designs, but in this case, I believe that it is Steeda copying UPR's Extreme Firewall Adjuster.
Either one would work well for you, but personally, I think that UPR has a better design than Steeda.