These are the specific modifications allowed by regulations in 2001 for Safari Rally:

4.1 Permitted modifications

4.1.1 The air intake for the engine of group 'A' cars may be modified by making a hole, of maximum 10cm diameter, in the engine bonnet only, in order to provide air for the engine through a 'snorkel', Appendix J, article 255.5.1.8. The air intake for the engine for group 'N' cars may be modified nsimilarly.
For group N cars, the addition of another tube from the bonnet to the air box is authorised. The air box may be modified accordingly, but must be identifiable as an original part and its position may not be changed, and the original air cleaner element must be retained.
4.1.2 Additional headlights, in accordance with Appendix J of the International Sporting Code, Articles 251.2.6, 254.6.7 and 255.5.8.5, are permitted provided that no light is mounted higher than the bottom of the windscreen.
4.1.3 Suspension travel straps are allowed.
4.1.4 All two-way radio installations are subject to authorisation and frequency allocation.
4.1.5 A maximum of two spare wheels will be allowed for all crews and these need not occupy the position(s) recommended by the manufacturer.
4.1.6 Mud flaps, in accordance with Appendix J, article 252.7.7, are authorised and are compulsory behind all driven and rear wheels and must be in place at the exit of all service parks.
4.1.7 Fitting of under body protections are authorised in accordance with Appendix J, articles 254.6.6.1 and 255.5.7.2.10. A cowcatcher in accordance with Appendix J, article 284.6.6.1, may be fitted.
4.1.8 The use of an increased capacity fuel tank(s) is authorised.
4.1.9 Competitors are reminded that translucent and colourless anti-shatter films on the side windows are mandatory. Silvered and tinted windows in accordance with Appendix J, article 253.11, are authorised, but have to be fitted in addition to the anti-shatter films.
4.1.10 Rear seats need not be carried.