Faster man ... 4,400KV? You will probably burn the motor or ESC or kill the batt if you want to stick to 3S. If its a 28mm motor 4,400KV is heck of a lot, unless you drop your prop to a 3". I tested out a 28mm x 40mm motor of 3,600KV with a 4.7x4.25 prop on 3S, she was already overheating.

How fast do you want to go? On 3S she is not that fast, on 4S to 6S she is pretty fast but you are talking about a lot of watts for not that much more speed with also the 'pig wallowing in the mud' handling because of the higher wing loading. I have tried her in 3S, 4S and 6S configuration. I favour the 3S with a light set up, a personal preference.

The FJ is nice to fly but its a draggy airframe, there are other planes out there where you can get really great speed with less watts put in.