Gold Wing engine design goals were smoothness, quietness and enormous power. Ultimately, a redesigned Gold Wing made its debut at the 1987 Cologne Motorcycle Show, 13 years after the original GL1000 was first shown to the public at the same venue, and the GL1500 brought the most changes seen to the Gold Wing series since its inception. The biggest difference was that the flat-four engine was replaced with a flat-six engine. Although the GL1500 still used carburetors, there were just two large 36 mm CV Keihins supplying all six cylinders, the first time any Gold Wing had less than one carb per cylinder. Honda also enclosed the entire motorcycle in plastic, giving it a seamless appearance. The seat height was lowest yet on a Gold Wing, the passenger back rest and trunk were integrated, and a central mechanism locked the trunk lid and saddlebags. Rear suspension air pressure was adjusted by an on-board compressor. One major innovation was the addition of a "reverse gear", which was actually a creative use of the electric starter motor linked to the transmission. Because of the size and weight, Honda felt that some people would have problems backing it up. The new Gold Wing had grown in nearly every dimension. A larger windshield, longer wheelbase, two more cylinders, more horsepower, more bodywork, more electronics, more accessories and more mass: dry. Options include a passenger audio control and rear speakers, CB radio, auxiliary lights and exterior trim. In another first for the GL1500, 1988 was the year Honda exported Gold Wings from the US to Japan for the first time. For 1989 Honda modified the brake discs, and raised the price. Brake discs were modified again in 1990, as were the carbs and camshafts, without a price increase. The claimed GL1500 dry weight for '90 was . In addition, a Gold Wing 15th Anniversary Special Edition model (GL1500SE) made its debut in 1990. The following year, to celebrate the 10th anniversary of American-made Gold Wings, every bike produced for 1991 came with a numbered plaque and anniversary edition insignia. There were three '91 models: Aspencade indicated the regular GL1500 model; the luxurious Special Edition from the year before carried on as the SE model; and the Interstate name denoted a stripped-down model. GL1500 Aspencade When the Honda of America Manufacturing (HAM) plant in Marysville, Ohio produced its 500,000th vehicle in 1991, it was a Gold