Mattis

Im going to start upgrading my sound system and i wanna make it as easy and cheap as possible, i dont have the logic7 system and i dont know the wattage at all for my amplifier, also im struggling to find out the wattage on any of the speakers, since i dont have the hk logic7 system i dont have a subwoofer, and ive been searching for ages to find out precicely what my specs are, im used to that u can oull out a speaker and both the wattage and impedance is written on the backside but this is not the case for either of my speakers, ive already replaced the front tweeters with two new 1inch aftermarket ones, and ive also installed a 3 x 10'' sub in my trunk so no complaints there, the thing im wondering the most now is what wattage my factory amplifier is and what wattage and impedance the center dash speaker is, ive speculated that i wanna replace it with an aftermarket 3,2'' midrange driver but this one is 20w rms and 40w max
and the impedance is 8ohm. i dont wanna mess up firstly because it takes a while untill the speaker gets shipped to me, about a month or so, secondly its kind of expensive and i dont wanna waste that money because im afraid that my factory amplifier is gonna struggle to give it enough power, i dont wanna buy a full range speaker because i feel like dedicated tweeters and speakers is better than a full range, and besides id have to redesign the speaker mount to an irreversible point to make it fit.