The main difference is the muffler. Most V6’s have a single tailpipe. The V8’s all have the dual pipe. Should be easy to fit a V8 cross-flow, dual-outlet in place of your V6 single-outlet muffler with minimal effort. You need the V8 tailpipes with the muffler, because the tailpipe outlets are offset to place them uniformly centered under the bumper.

If you buy a complete cat-back system, the muffler and tips should interchange. But the V8 intermediate pipe might not connect to the cat outlet in the same place on a V6 car. May or may not. That’s why I only mentioned the muffler.