The new FD2 IM is pretty much the exact same as the RBC mani, it just doesn't have the inlet valve for the throttle body. One would have to do way too much work to get the RRC mani to work on the DC5. And still would an adapter plate for the throttle body as the new one is DBW.
I know I instantly felt a difference when I installed my RBC over a month ago. No dyno numbers to share as I don't dyno my car at all. The car revs more freely (at least it feels as such) and just wants to get up and go throughout the powerband. If you have a KPro, you can take even more advantage of it. The runners are a bit wider in diameter over the PRC and also are straight and the air doesn't have to fight the manifold to make its way into the motor.
AC doesn't have to be removed. As stated, the bonnet arm needs to be removed and that is about it. The AC line also needs to be disconnected and the little black brackets reconfigured some and then mounted back to the rad support. I also slightly bent my rad support towards the front of the car to give even a bit more clearance between the mani and it.
I also had a friend fab up an aluminum pipe to replace the stock rubber intake arm.
