S8 exhaust will it fit
 

Hey guys I have a 2006 A8L and I was thinking of putting on the exhaust from a 2010 S8 My local dealer says it will work but I wanted to get some other opinions or if you see any problems in doing this. Do you think it will make the care sound any different and preform different?

The fitment depends on where it starts. The systems are near identical from cats back and you really couldn't go closer to the engine without major modification. Probably more of an appearance thing and "maybe" slightly different sound...both from the only real difference: twin pipes exiting each rear muffler, rather than one each. IF you were to get less restriction, it would likely just move power from low end (softer lift off) to the top end (not mention worse mpg's...need certain restriction with a given engine)...then you'd need modification to gain higher redline to use it: ECM, cams, injectors, etc.
The exhaust switch alone would probably do almost nothing.
In older D2 S8's, NONE of the extra power came from exhaust mods...exactly the same on A8 and S8, except chrome tips. All the extra HP came from cams, intake manifold and injectors, which just allowed a higher redline...almost ALL the extra acceleration came from lower differentials gearing. A same year D2 A8 with S8 gearing is just as fast, except on the upper above 6400 rpms.