I care about the weight savings more than anything else. For my autocross class, only catback exhausts are allowed. On top of that, I'm in CA, so all 4 cats need to stay.

Between having all 4 cats and the h-pipe, there should be sufficient scavenging on the exhaust.

The one caveat is that I'm concerned about not passing sound -- it's 92dB at 50ft in my region, so that's why I had a flange added in the event I need to bolt the muffler back on quickly. If I need to cut the noise down permanently, I figure I can always change to a turndown or cc insert.