Quote:
Originally Posted by wileecoyote
Seems like there's a number of S4 owners on here, maybe they'd have some input as that is a twin turbo platform which is pretty well evolved. Maybe they have some experience one way or the other.
I'd really like to hear from some of the exhaust manufacturers as to their thoughts like Vishnu and AA for instance since they are fairly active here.
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There's no such thing as an x-pipe in the S4 world. I had a Milltek SuperDual exhaust that had two pipes, one for each cylinder bank, and they never intersected. Amazing sound, btw.
From my understanding, the 'x' connection is there to pull exhaust pulses from the other side (same thing as was mentioned in the beginning of this thread). In a turbo charged car, you want to get the exhaust gases out of there as quickly as possible with minimal changes in direction. With an x-pipe, you're forcing the flow of the two pipes to intersect and basically push past each other on the way out. It's a bottle neck.
I think of it as a fan (exhaust turbine) that's pushing the air out. It's a smooth flow that doesn't like to be interrupted. The x-pipe interrupts the flow. BMW must have their reasons for putting it in there but I seriously doubt it was to improve performance.
My $.02