The current front bumper on my car is from an Audi RS4. It’s not a direct fit because the Audi RS4 has flared front fenders/front bumper thus the bumper needs to formed to fit my “non-flared” S4 fenders. The pictures below show the difference.
It’s not the easiest job but it’s certainly something a quality shop can do. I’ve seen several kick ass jobs from other cars across the country… and I’ve seen some pretty bad ones too. My current RS4 bumper has never fit perfectly and this time I want to make sure it’s damn near perfect… like this…
Yeah that looks pretty bad if you did just the bumper and front fenders but no side skirts or rear fender. Cost-wise, it would be best to have the rs4 front bumper and then just modify your current front fenders if possible. To do the bumper, front and rear fenders, and skirts, it would probably cost a ton of money. IMO it looks great either way though.