Quote Originally Posted by David88vert View Post
You do not need an ignition module to use a PC3. A PC3 controls the fuel injectors, so that you can optimize your A/F ratio. It is usually used when you change something like your intake or exhaust, to flow more air. The additional air can require more fuel to be added to maintain an optimal A/F ratio. SOME bikes can see a small improvement when stock, but my experience has been that it is not necessary for most modern stock street bikes - especially new ones that have better mapping from the factory.
He nailed it.

If you're running some significant exhaust and intake changes I'd recommend one, but nothing else is required with them.