I have the Pioneer f90bt and now want to change speakers and amp. I looked today and I have 3 speakers in the upper dash ( proabably 2 inch tweets and a bigger spkr in the middle), also in the front doors I have a 4 inch slot not used and a 7 or 8 inch slot used. The back panel has 6 inch and 2 inch slots, both used. Im assuming the 2 inch ones are tweets in the back panel but not sure what type I have in the front doors (maybe woofers?) or back panels. Would anyone have an idea? I want to replace all speakers and use the 4 inch slot that is not used. I want to go for around 400-600 amps total. What speakers and amp should I get? And will I need a 4 or 5 channel amp? SO for the front door since I have a 4 and 8 inch slot what should be used? My current setup is 140 watts max and sounds pretty good so I dont want to go super high the watts department and dont want to do any box addons for woofers. Thanks.