Should be around the 15deg I think
If it were me I would want It bang on that I dunno if tha 2deg adv will cause detination
But if u had it set a 25 deg bftdc that defiantly would not of helped anything and would have no doubt been detonating or not far of it :-/
Also most of the RBs I have owned have usually have there cas set in the middle .
Only once have I had one set on max retard and that was when my cas was on its way out and started advancing the timing randomly hahhaha
Good luck buddy