Hey, I've got a 2003 Gt with the Mach 460 sound system. Shortly after I bought it the CD Player went kaput and after looking around I figured I would be better off replacing the head unit and speakers rather than take a chance with fixing the old CD changer. I picked up a JVC headunit: http://www.bestbuy.com/site/JVC+-+5...Deck/9766673.p?id=1218169733468&skuId=9766673 and also 2 pairs of speakers: http://www.bestbuy.com/site/Kenwood...air)/9764384.p?id=1218169465316&skuId=9764384 I also picked up a 4 channel amp: http://www.bestbuy.com/site/Polk+Au...oost/1007116.p?id=1218207656847&skuId=1007116 I installed the HU and the 4 speakers. I wired the speakers into the stock tweeter wires. I have not installed the amp yet. The system just does not sound right. The lows are not very punchy unless I have the "loud" feature turned on but then the highs sound too loud. I've heard that sometimes 2 high quality front speakers sound better than 4 mid quality ones. Any opinions on this? I would like to add an 8" sub to add some more bass. I was also thinking of mounting the rear speakers in a vertical plane on a panel flush mounted to the back of the seats and than run the system with the seats down. Would that help the sound staging? Most of the sound seems to come from the back, but if I fade some to the front speakers they just don't sound very good. Any suggestions? Thanks for your time.