Nothing. CDIs are used only in machines with carburetors. All Brutes after 2008 are EFI and use ECUs. You can have the ECU re-flashed which may give some extra power and raise the rev limiter however many have found they lost power or performance as all Brutes after 2015 have a state-of-the-art 64bit closed loop system tuned very well from Kawasaki for the existing systems such as it's exhaust and intake. Destroying it has proved fruitless in many cases unless other things are also changed such as adding a BBK, full aftermarket exhaust, larger throttlebodys and injectors, cams....ect. Most don't do all that until it's time for a full rebuild. My advice..tune the clutches if you must but leave the rest alone and just enjoy perfection.