HKS Carbon Ti Hi-Power Exhaust 1993-1996 Mazda RX-7HKS Carbon Ti Hi Power Exhaust 1993 1996 Mazda RX 7 HKS Hi Power Muffler came back with the same concept, "High Power & High Performance", and "Resonant Sound" and "Stylish" are harmonized together. To maintain the exhaust efficiency, enlargement of the exhaust pipe is usually required; the sound level tends to be increased and low tone. The exhaust system with a cannon ball shaped shell usually has lower silencer capacity than an oval shaped shell;