this is why I don't post anymore.
Do you have any idea the amount of development work I did on my k11?
The testing with and without a mesh was very low on my list. Common sense I would think would normally explain this.
Ahh ###### it, I won't post my opinions anymore.
Turbulent flow is good flow, also it will make 0.0000000001% of a difference to your performance. Where as the crap I have seen gather on here will make a difference to your performance if it ends up in your engine.
I'd go for a 2/2.5" system with a CAT in the location of the standard second one. One K11 owner I know uses a gtir CAT on a 2.5" system (with appropriate engine management) and passes his MOT no problem.
For info, a turbo will almost always IMPROVE/REDUCE emissions, not make them worse. A too...