In that case, go with the ERZ/CNT catted downpipe. It's a full 3" with a bellmouth. Much more flow than a shorty + 3rd cat. I had a Bosal (same flat flange design as Stromung) and switched to the ERZ. The cat is effective at passing smog and cutting down noise and smell. And it's cheap. I was closer to failing smog with only the stock 3rd cat v. ERZ.