With places and two outright wins at Brands Hatch in his first season, after graduating to a higher level with places in his second season at other circuits, Dunstall retired from racing to work in his family's scooter shop and develop performance motorcycle parts[3] Initially, Dunstall conceived simple 'bolt on' modifications such as 'Goldie' pattern straight-through replacement silencers which he called 'Hi-Tune'[8] and exhaust pipes, creating his first catalogue in 1961 and gradually growing the business.

[citation needed] For the 1969 season, Dunstall created a new machine with a lower frontal area, the inclined engine being 'underslung' from a large-diameter steel tubing spine frame (nicknamed The Drainpipe) designed by Eddie Robinson.

[16][17] Motorcycle News' 1980 table of top speeds listed the CS1000 as number one and Dunstall Suzuki GSX1100's 144.5 miles per hour (232.6 km/h) at two, followed by the Moto Martin CBX at three.

[3] In 1967 Rex Butcher (Dunstall's shop manager and regular rider) - supported by Motor Cycle (a UK weekly publication) journalist David Dixon on a second machine - set a number of world records on 750 cc Dunstalls at Monza in Italy, using two machines earlier ridden by Paul Smart (2nd place) and Griff Jenkins (11th place) in the 1967 TT Production race 750cc category (both recorded as 'Norton' in official race result website).

[19] In his 13 September 1967 Motor Cycle article, Dixon reported both bikes were the same production TT race specification with lighting and (road-legal) megaphone-style silencers but had been stripped, checked and re-built, with special preparation being limited to larger six-gallon petrol tanks, modified racing seats, improved fairings from the forthcoming 1968 range and 45 psi tyre pressures.

[24] In June 1968 Pickrell won the Isle of Man Production TT race 750 cc class entered on a 'Dunstall Norton Dominator' with a new lap record (average speed) of 99.39 mph (159.95 km/h).