This is the biggest and baddest bolt-in engine for a stock frame. S&S has designed every part of this engine to make it fit 2008 and up Harley Davidson® Touring chassis with no frame modifications required. The B3 heads were designed specifically for this engine, optimally locating the intake and exhaust ports while still providing the correct flow. The contour of the rocker boxes has been addressed to clear the frame. A proprietary 70mm Throttle Hog and Stealth air cleaner have been designed for this monster to allow it to breathe. Sure this fantastic engine paint a smile on your face when you twist the throttle.