I would say it's more CPU bound in it's current state. While the graphics card helps, when I upgraded from a 570 to a 780 I only got about a 10 FPS increase. I was using an AMD Phenom II x4 965 then. When I upgraded to a 4770k (and obviously new motherboard; MSI Z87 GD65) I went from about a 40-60 average FPS to over 100-130 depending on number of objects in the sim.
Also, congrats on the TIR. It really is a whole new experience. You may want to look into getting some rudder pedals to go with your warthog too.