The 2012 Mazda 3 with Skyactiv-G has a compression ratio of 12:1 because the 4-2-1 exhaust manifold doesn't fit in the engine bay.

Enter the Edelbrock dual-quad intake! Recognizing the inherent coolness of dual-quad induction, Edelbrock designed a dual-plane, RPM Air Gap, dual-quad manifold for the modern Hemis.