^^^ Lamborghini diablo has a .19 drg.c and the C5 Corvette has a .21 drg.c. I don't think .29 is that great, IMO. But to reduce drag, you can do quite a bit. First off, a belly cover is a good idea. Most expensive high performance cars have them because they reduce the air bubble under the car preventing lift. Next, you need lower rolling resistance tires... (This only reduces drag and it's not good to go fast without grip, so I don't recommend this). You'll need a good front aero kit. Not every body package removes drag... Some add drag. So you need to pick wisely. Next, fold in your side mirrors (or remove them) and remove your wind shield wiper.
At speeds of 120+Mph, you don't need them anyway. Then you'll need to lower the car as much as possible. Stiffer suspension would be required to handle the down force. You'll need to shave your door handles and anything sticking out of the car in any way shape or form, you'll need to remove.
All that should get you down to .27 or .26 Drg.c LOL!