Perhaps thet didn't elude to the Group B S4 because more great drivers got killed in them than any of the other GRoup B cars i can think of
The "GREAT HENRI TOIVENEN" Whose death unfortunately was the last straw for Group B !
Perhaps roumours of using Nitrous in the fire extinguishers didn't help !
Cut my teeth on 6R4's then RS 200's but never had much to do with the S4
Did do an engine for an Alitalia Stratos tho :D
Probably no quicker than a good Gpn Subaru or evo with modern technology