jmayfield23

Does the d3 a8’s have the butterfly exhaust valve? Or is that just for the s8?

Timur_lenk

W12 has too.

jmayfield23

So the 4.2 doesn’t?

MP4.2+6.0

I don't recall that 4.2 does, but just look under there and have answer in 60 seconds or less. It is right at the final outlets behind the bumper cover.

Realize that both the S8 AND W12 are really a total of four pipe outlets to the twin rear cans. The W12 buries them in the big bucks trapezoidal bumper cutout, but deeper in there is a set of twin outlet ports for each can. one of which is flap controlled on each side. 4.2 is just single main outlet to each can IIRC. The pipes all the way through are also upsized in general; the flaps help with more back pressure at lower RPM to increase torque with the overall higher flow system. Keeps it a bit quieter at low loads and RPM's too.

dvs_dave

Nope