fyi; jwt uses 25* base timing on their "big cam program".
this includes the S5's and C1-C3 cams. not sure of the others. it's part of their "idle stability" programming. the target idle speed is also raised to ~900-1000rpm. i've suggested in the past on _the other forum_ that before installing big cams it helps to set the timing and idle for the big cams, before the swap. because, like Ben said, the lope of big cams makes it VERY difficult to get either right, after the swap.
(hint) if you haven't yet...you'll need to adjust the target idle speed also. since the big cam program uses ~900-1000 rpm as the target, if your's is still set at 800-850 rpm you'll get whats commonly referred to as a "hunting idle). the ecu tries to keep the engine at its programmed (in this case 900-1000) while the the physical idle adjustment is at 800-850, constantly fighting each other.
it sucks that you've been chasing ghosts this whole time
. the car should run MUCH stronger now that the base timing is correct.
when you're ready, i'd suggest either a calum rt (if you can find one) or nistune.