if its rear deck bay is same as old city then u can not fit 6by9 speakers in oroginal fittings
the kenwood cassete player/cd controler which comes with it can be sold for 3000rs easily.
u can get an mp3 wala pioneer and kenwood indash player for 7-8000rs
sirf cd wala 5-6K
or u can get kenwood 12 cd changer for 6K and run it with ur factory fitted casste/controller, per wo mp3 nai ho ga
btw max size u can put in the back original fittings is 6 3/4 inch