Skoda fabia 2 2011 vrs

Probably been on previuos threads but just looking to upgrade the standard speakers to better quality ones front and rear . That are straightforward diy jobs presume the standard skoda ones have a plug you have to cut off and put crimps on . Any help would be good also is there a sub that dosn't take up too much room in the boot that is powered and can just be added to the standard fit swing stereo. Cheers