I used for all races P206 WRC, slightly tuned for easy and normal races, and fully tuned for hard races (came in handy when fighting that hardcore lancia S4 on several tracks and the 787B on wet tsukuba). All I did was to make a setup for tarmac races (lowered car, harder suspension more camber) and another for snow and gravel (higher, softer, less). I don't think I tinkered with gearbox at all (not suer, but I don't think so).
Sure, P206 WRC is expencive, but it serverd me very well on those races and it helped me to cruise through 206 Cup under manufacturer race.