just cars charge extra per mods up to a certain point then there is no extra charge for extra mods - my just car covers:

Cam, Superlows, Trans conversion, Slotted Rotors (and any other brake upgrades, provided legal, so ADR braided lines and 330mm rotors if I so decide), extractors, exhaust, diff changes, air filter, aftermarket cruise, alarm, c-locking etc, tinted widows

whats the max??? with all that how much is excess and premium if u dont mind me asking

i wouldn;t bother telling them, if you write the car off, they arn't gunna strat it up and wonder why it's so lumpy.
and changing the cam can be seen as part of an engine rebuild.
and you can't see that it's an aftermarket cam without removing rocker cover etc. and looking...