Catback or Catless Downpipes

[Scrain]

What would you recommend, a catted Unitronic downpipe or a valvetronic catback exhaust? I understand a catback exhaust would make less power than a downpipe.

The Unitronic downpipe is listed as needing the stage 2 tune from Unitroinic which is a little confusing as to why that is important. I have the stage 1 plus tune currently.

Does a downpipe improve sound or does it just make the car louder? Whichever would sound better is the option I would go with considering they are both around the same price.
Thx

[jzhu625]

Catted DP will give you much better sound and louder.

[PunjabiM3]

Is there a consensus on which brand catted DP is the best to go with as far as power and no CEL?

[Krueger]

I highly recommend you go with the catted DPS. Modern day sport catalysts flow like 96% of what catless DPs flow. The difference in power gain between the two would be negligible.

[kjcncsu]

Is there a consensus on which brand catted DP is the best to go with as far as power and no CEL?

I've had the Uni ones on for a few thousand miles without a CEL. Redstar makes one with the same GESI cat so should be fine with that as well. I've also seen multiple reports that the HJS cats are also good to go without triggering a CEL. I think Soul, Fabspeed, and Redstar all offer DPs with the HJS cats.

[Scrain]

I've had the Uni ones on for a few thousand miles without a CEL. Redstar makes one with the same GESI cat so should be fine with that as well. I've also seen multiple reports that the HJS cats are also good to go without triggering a CEL. I think Soul, Fabspeed, and Redstar all offer DPs with the HJS cats.

Thank you!

[OneFastBMW]

Fabspeed uses the HJS 200 cell cats and guarantees no CEL (at least on US cars).

As stated earlier. You 100% want cats. There is negligible, if any, performance or sound difference between catless and a high flowing cat.