Actually it is universal with all engines, however some engines respond better then others do.... my Clocked engines respond extremely well to tuning by tuned pipe, with a more dynamic performance change as opposed to a stock engine........ On some pipes my modifieds will only be slightly stronger then stock, then other pipes will make nearly double the power the stock engine would.. and in some rare cases the modified may make less power on a particular pipe then the stock engine would.......You would be amazed at how much that BTT will change when you take that 86 off........ Those modified BTT's are super potent on the 9886 pipe...one of those combinations that the timings match up well and it makes power beyond what it should for a 4 port......