New stainless steel exhaust on S8 D2 (with pics)

[ainarssems]

My exhaust needs doing really soon, I have rattling cats. I really want a X-pipe but worried about its placement, worried if it will create drone, and if it will be the correct shape to release more HP. A badly made X-pipe with rubbish cross-section merger will probably rob HP so its a real risk.

I think any reasonably made x-pipe will be better than factory H-pipe overall but H-pipe might deliver a bit more torque at low rpm at certain scenarios. There is no such thing as best x-pipe for all conditions, it's a compromise. Pipe size, location, entry and exit angles as well connecting cross-section will determine at which rpm it will increase torque more. If you want to make it simple and generalise then steeper angle and closer to engine will increase high rpm torque and max BHP at cost of low rpm torque. Shallower angles and further from the engine will give more low end torque at cost of max BHP.