they did, its was alfas doing that the new wings and splitters were enforced in 1995.
once alfa started using them, got banned for using moveable ones, when the road cars were fixed, then came back after missing a round at oulton park, with fixed splitters and wings, every manufacturer started making them for the road cars so they could use them on the race car.
1st renault followed suit with that massive boomarang on the laguna, then bmw came with m3 kiited bm's as the kit was made standard accross the range on the road car. peugeot already had them on the 405, the mondeo started using them on the v6si so the team did.
so they made them a homolgation standard in 1995 and could be no higher than the roof of the car, so volvo had the biggest challenge and had to change there car completely
mid to late 90's was best, and contact is going to happen, rubbings racing so the saying goes
and remember the cars weigh nothing over the back wheels so the slightest little contact and around they go, makes it look more malicious than it is.
as quoted by charlie cox, "you could reach out and push them round with your little finger"
great commentator, made very good and funny viewing
BMW didnt have intake restrictions for rwd. bmw and audi had weight penalty's for the advantage they had