All 'Cup' models were relieved of their rear speakers and couldn't be spec'd even if you did want them from the brand new. Pioneer do a direct front and rear speaker replacement that doesn't require a 'spade' converter. I've got these in my car front (inc. tweeters) and rear only cost £75 and there is no distortion even up to the volume you relate a Nova with haha!
Are they the ones to go for then ? i want to sort it out like