I believe the M4 requires some cutting of the stock exhaust, essentially you cut off the section with the cat. This is what makes the M4 sound so good and why our bikes still sound like a sewing machine with just a traditional slip-on added. Having cut out the catalytic out of the system, the bikes will "pop" and sometimes flame as the exhaust gasses are now out of whack. The block off plate will help reduce the pop, especially on deceleration. The fuel control (dynojet, Bazzaz, etc) will be needed to realize power gains as well as a more useful powerband.
You can do just the M4 and block off plate first, then wait to add a fuel controller.