The championship runs under BRSCC Grp N rules....section from there technical regs reads...
5.6. BODYWORK: GROUP N
5.6.1. Modifications Permitted:
5.6.1.1 Removal of spare wheel and tools.
5.6.1.2. Alternative steering wheel.
5.6.1.3. Non-standard driver’s seat.
5.6.1.4. Removal of floor carpeting.
5.6.1.5. Removal/replacement of passenger seats.
5.6.1.6. Removal of passenger compartment heater.
5.6.1.7. Fuel and brake lines may be routed through the driver habitacle subject to provisions of MSA Regulation
[C(c)
103 & 104].
5.6.1.8. Silhouette
No change is permitted.