Taking our stage 3 kit a bit further, we use the complete S&S M8 124 and 128 kits for our stage 3.5. The cylinders are stronger and larger than we can safely bore out the stock cylinders to, yet still fit the M8 crankcases without any additional machining. The 107 becomes 124 whilst the longer stroke 114 and CVO 117 becomes 128. The kit includes a superior S&S oil pump and cam plate, as well as lifters, pushrods, stronger valve springs and a cam. At this level of performance, we need to give careful consideration to the exhaust system and air cleaner in order to maximise the benefits.