i just finished my manual conversion on my 96 rs4, i used a r34 gtt clutch pedal and a r33 master cylinder and didnt need a booster and you dont need to recess it. only the gtr clutch pedal is recessed into the firewall, i think all gtr clutch pedals are recessed, same with the autech gtr stageas. so if you have a r34 gt-t clutch pedal you should have no problems, they are hard to get tho i waited 6 months and didnt see 1 any where so i had to order it from nissan $780 NZD
should be lots around after the earthquake and all. hope this helps,
Johan