I have a 2006 WRX TR and am interested in upgrading the sound system. I currently have the stock premium speakers with the sub under the driver seat. I'm looking to get new component speakers for the front doors as well as new speakers for the back doors. I've been looking on crutchfield and it looks like JBL or Infinity Kappa are the best way to go. Anyone have any experience with these? And if I upgraded all the doors would I need to get an amp beyond my pioneer premiere stereo? Thanks!