Thundersport has been forced to trim its September Mallory Park meeting to just one day as restrictions at the Leicestershire track mean a clampdown on the amount of noisy days left on its schedule.
Following legal action by the local authority, Mallory is struggling to accommodate all of its events to the end of this year, so instead of moving their event to another venue, Thundersport will just run on September 29.
"Our rounds at Mallory Park will now revert to the established 1 day format, with silver and gold races as per our normal Oulton Park format," said Thundersport boss Dave Stewart.
"The regular four-race classes will score double points for each of their two Sunday races and the Sportsman Elite 600 & Thundersport GP1 races will score normal points for their first race and double points for their second race of the day. This arrangement is to maintain our 675 point/900 point championship criteria, as per the Supplementary Regulations.
"We apologise for any inconvenience, but hope that you will join us in supporting Mallory Park at this very difficult time for everyone involved with the circuit.
"While not wishing to get involved with the ongoing debate over the rights and wrongs of the case itself, this is very much a situation where the expression 'Use it, or lose it!' applies and we feel very strongly that we should defend our sport and the arenas we need to continue with our passion."
Stewart confirmed the entry fee will be adjusted accordingly, with a £125 fee covering a normal one class entry and an extra class being an additional £50 fee.
