After two years in World Superbikes as a privateer Ducati team, Supersonic moved to BSB in 2012, entering Tommy Bridewell and Patric Muff on BMWs.
Bridewell in particular impressed, coming sixth overall as Supersonic made the Title Showdown, but his team were concerned at BMW's lack of backing and have decided to support former BSB rider Alex Polita in Italy's CIV Superbike Championship instead.
The former Italian champion will ride a Suzuki GSX-R1000.
Bridewell is now looking for a team but should have several takers after his breakout season.
Meanwhile, BSB will be without two of the six teams that made the 2012 'Title Showdown' – Supersonic and Team WFR – while MSS Performance have also taken a year off.