What advantage is there by swapping the stock Heads on a 500 EFI to a set of Brodix BB-2Plus? I have a set that is available too me. I will be changing all the other components that are needed to make the the Transition, Larger Throttle Body, Ignition, Reprogramed ECU, ETC.

Heads have had a moderate flow increase and a bowl blend already. Intake size is 312cc.

Sounds like a nice upgrade. I would expect 50-75 hp. don't take my word for it though.

Make sure to fresh water flush them a lot.

Be Careful on going to big on heads with not to much ci. You will need to raise the revs to 5800 rpm's to get the power gain with the heads. Remember your torque band will be higher therefore you need higher rpm's to get power out of them. You will lose some power down low. Personally I would just change to monoblade throttle body and raise rev-limit. 20-30hp increase.