Do you really have to be 100% honest with your motorbike insurance company ?

Ive just taken out 3rd party fire&theft insurance cover for my Aprilia, Im now thinking of adding a K&N filter, Akropovic cans and a Power Commander. As Im only goin 3rd party would you bother to tell the insurance company of these extras ? I mean, if I hit another car Im probably going to dead and I wont be paid out for the bike anyway, so why tell em ? What do you think ? Cheers.