My opinion I think you need a programmer, it can pay for itself down the road when you decide to upgrade internals on your motor, air intake etc, I've never ran a pipe (slip on or full) without it. Everyone has their opinions on this, but if you want your Outty to run to the optimal level it should have one. Just my $.02. Have fun with the pipe, nothing sounds better than an uncorked v-twin, luv it!!!