My f/r lips are modified .. did it ~mid-80s.. to accommodate 16x10 (5" bs/0 offset) race rims with 275-45-16 Hoosier autocross tires.... the fronts are easy... my best friend is a body shop owner... he carefully tugged and pulled, as well as rolled, the fronts... one night for both fronts.
The rears were more tricky.... he cut the factory welds, carefully tugged/pulled the lips out, re-welded the lips, epoxy coated smooth inside. took one-night each for the rears.
The over all result is a factory appearance, whereby, the chrome trim could still be installed if desired (but not needed or wanted by me). With my car lowered for autocross/road racing... with the then biggest 275-45-16 tires (for competition purposes), the tires cleared within a pinky finger.. no rubbing, even under severe cornering... and my suspension is stiffly setup (1.24 TBs, fiberglass mono Flexaform leafs @ 225#/inch, flat... and stiff Konis red "D" shocks f/r, and sway bars 1.25" f, 1" r)... car handles flat and superbly.. and rides great on the street/hwy (better with BFG T/As 255/60 f, 275/60 r both on 8" wide minilite vintage rims).
The fender mods look stock.. only a well trained eye can tell the difference with another stock Challenger next to mine.