newbie needs help

my car comes with a factory fitted cd player by philips. it comes with 2 front tweeters, 2 front door speakers that i have replaced with 135w JBL 5 1/4 and 2 speakers in the back shelf of the boot/trunk. i have stripped the wires of the boot/trunk speakers and have connected 200w alpine speakers to them. my first problem is that the sound is not much louder and i arent getting more bass than the stock speakers. so how do i make it louder/more bass without new HU or an Amp. my second problem is when i turn the volume loud and the stock speakers in the boot are connected and also the alpines are connected there is a crackling sound coming from the speakers. but when i disconnect the stock speakers while the alpines are still connected and working, the sound is OK in high volumes. *boot means trunk

In general, you cannot get it "louder" by simply replacing speakers.  The "loudness" is created by the amp inside the factory head unit.  The only way to get much "louder" is by adding an amp or replacing the head.  New speakers should make it sound "better," however.  Secondly, do NOT connect a second set (your Alpine speakers) in parallel with the factory speakers in yor boot.  REMOVE the factory speakers.  Putting two sets in parallel like that will eventually blow you head unit as it is placing too low an impedence load on your factory head unit amp.  Fix this now.Support the12volt.com

You will be getting most of your sound from your front speakers. The back speakers do not matter as much they are just for rear filler.  Put the best speakers you can afford up front.