it would still work with the pieman module. The pickup head itself is moved relative to the flywheel. Prior to retarding the timing I had some issues with knock on hot days or with lower octane gas. The idea was suggested by D&D as they had similar issues with their turbo charged bikes.
the picture shows the retarded pick up head.

05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter