 I love my GT/CS. The performance is very exciting and the 4.6 does a nice job to really get this car moving. I have an auto and its no slug, it will get up and move when you want it to.  The drop top is a very nice feature.  Easy to operate and fairly quick to raise/lower. Due to the live rear axle you can experience some drivability issues when pushing the car around a turn with bumps in the road, not enough for me to really consider it not drivable when pushed.  I have the shaker 500 and its loud enough to hear with the top down while driving 80. For MPG you can get good numbers if you are being very good.  Top down 18/24 and up 20/25.  You can have a new car with just a few mods, enjoy!