This one is special. Royal Pontiac, located in Royal Oak, Michigan, offered a 428/Royal Bobcat conversion of the 1968 GTO. For $650.00. a 390 horsepower 428 cubic engine was installed in place of the 400 cubic engine. The 428 CI engine was disassembled and blueprinted to produce more than the advertised factory 390 horsepower and easily spinning to 5700 RPM's. Car and Driver road tested the 428 CI powered car with the 3.55 gears. It could do 0-60 MPH in 5.2 seconds, 0-100 in 12.9 seconds, and the 1/4 mile in 13.8 seconds @ 104 MPH. his compared to a Car Life road test of a 400 CI powered GTO with a Ram Air engine, 4-speed transmission, and 3.90 gear which did 0-60 in 6.6 seconds, 0-100 in 14.6 seconds, and the 1/4 mile in 14.53 @ 99.7 MPH. Car and Driver wrote that the 428 CI powered car was "a fine, exciting car for either touring or tooting around in traffic. Not overly fussy. Not difficult to driveā€“-up to a point. Too much throttle at the wrong time will spin the car, or send it rocketing off the road and into the farmer's field. You can light up the car's tires like it was an AA-fueler anytime the notion seizes your fancy."