If it LOOKS restrictive I'd replace it. But LOOKS may fool you. While observing the dent think about the area inside the dent and conclude whether or not it is simply a change in SHAPE or if it actually is squeezing the exhaust at that point and lessening the flow.
If the flow is lessened...GET A NEW ONE!!
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist