More displacement and performance - go fast! Increased fin area for better heat dissipation - be cool! Increase bore size from 3.750" to 3.927" - bigger is better! Easy installation - no machining or rebalancing required - economical! Cosmetic improvements - Hard to tell from stock cylinders 11 fins and full fin pattern on cam side closely resembles OEM shape S&S Logo and part numbers are less conspicuous Better overall appearance