ATP blow off valve flanges are the solution to installing a universal Greddy BOV on your 07-10 MazdaSpeed3. ATP blow off flanges are a direct bolt on to the MS3 top mount intercooler, or front mount intercooler utilizing the same flange. These setups will only vent to the atmosphere.
The HKS mounting flange for the Mazdaspeed3 is only needed when used with a universal fit HKS valve. Any kit listed as 'Mazdaspeed3 specific' will already include this flange.