[BigHeadClan]

The CATS are the biggest restriction in the Q50/60 exhaust system with the turbo engine, if you plan to get a ECUTek/JB4 tune at some point I strongly suggest
you do the Downpipes as well. It will be cheaper to do both at the same time anyhow.

 

[BigHeadClan]

As my long-winded friend above was saying Lower Downpipes and a CBE is the way to go, included a picture below of the typically
layout if you still feel a bit confused.

 

[BigHeadClan]

Your pic is misleading. Calling the 1st (primary cat) the "second", and secondary cat the "third". Just saying ? Unless there is something I'm missing.

Hah yeah it doesn't label it 100% correct, was more of a generic example of the layout of the system and how it's broken up into sections.