Lamborghini showcases its open-top Aventador at the LA Auto Show.After officially popping its top a couple of weeks ago in Miami, the new Aventador Roadster has made its public debut at the Los Angeles Auto Show. Lamborghini has priced the convertible supercar a shade under $450k. For that you get the same mechanical bits as the coupe - a 6.5-liter V12 with 700 horsepower on tap driving all four wheels via Lambo's seven-speed sequential transmission - but with the chance to enjoy that sumptuous engine note with the roof down.Whenever you want to go topless, however, the Aventador LP700-4 Roadster's 6kg carbon-composite two-piece roof must be removed by hand and stored in the front of the car. And judging by how awesome it...