Retarding E16SE ignition timing

[MK999]

Fixed the timing on my E16SE recently so it's no longer pinking, however it's now lost a bit of it's guts and also doesn't seem to make the same blarp/burbley intake sound, which seems to suggest to me that the cam timing was much nicer being more advanced but the ignition timing was too far advanced, is there any way to retard the ignition timing relative to the cam? It's all 'notched into' the block etc so the only thing I can think of is expanding those notches, but then it won't hold steady?

edit: it's the bosch 'clip on' type dizzy btw