If you have turned the FWA clockwise as far as you can (making the FWA itself as short as it can be) and the cable is too tight, see if you can switch hooks on the quadrant (I think you got a Steeda quad, which might have two hooks).
If you can move the cable 'out' one hook on the quadrant (having it attach at a hook closer to the firewall, is possible), that will add slack to the cable. Then readjust the FWA as necessary.