Just rethinking this, I don't know the tuning parameters of the Ultimate... but seeing as the whole air speed and velocity changes from the RBC I think a lot of the torque loss is just in the ECU not knowing how to capitalise, not the actual design of the RBC.
From what I saw with Darren's car, he made good torque even with his mid-level headers, intake and restrictive catback. Seeing as there's so much power in an engine like the K24 in tuning, you might as well give the RBC a try. If you could retain the stock torque up until about 4500rpm then surpass it after that then you're ahead in my opinion. From your sig you seem to be a bit of a track whore, and on Wakey there isn't a place where you'll drop below 5000rpm in 2nd :)
Also from my recent experience, RBC matched with flywheel is pretty potent stuff. I run my tyres on 32psi and the car is 50/50 on whether it spins in 1st from a rolling punch. If you could do your flywheel + RBC + tune I think you'd see impressive results in a real life situation.