yeah martin you may aswell "upgrade" a lilttle. i got some 6.5 in speakers and adaptor for my doors but wheni finally took e apart i found that tha previous owner upgraded both the rear 6.5 anmd the door 4x6 to audiobahn. so i returned the speakers and have the cavalier kit for the front doors if u really wanna upgrade em. i just couldnt get rid of brand new audiobahn 4x6 speakers for some reason and left em there. so if u wanna upgrade u can have my adaptor.
probably be easier to find p11 6.5's (for one they had 4 of em stock as the p10's only had 2, and secondly i dunno if there is any working p10 stock speakers still around; they tend to be dried out and destroyed by now). i put 2 p11 bose speakers in my rear deck in my winter beater p10 and they sound great.