which I think are vibrant are too big to work well. They have the ID that support a 2.8-3" pipe but OD that allows you to pinch it between flanges of almost any size.
Greddy did some custom stuff with their cat back systems where the flanges are not quite angled properly to be universal - so you get bad fitment with SZ test pipes, for instance. I ended up getting a SZ X-pipe and then fitting the greddy exhaust to that. It still required some work with my hangars to get the tips looking right. Very weird.