Originally Posted by jcorreanyc

What's interesting is the piping between the cats and the center resonator (for the V8s). As it turns out, the 4.4's from '00 to '03 had a 50mm (2 inch) downpipe on both sides. The 4.4's from '04 to '06 (N62 facelift) had 55mm downpipes (2 1/8 inch). The 4.6is interestingly had a 55mm downpipe on the driver side and 50mm on the passenger side! The 4.8is had 60mm (2 1/4 inch) downpipes, hence the throatier sound.

From the resonator back, it seems that 3.0, 4.4, and 4.6's all had the same diameter pipes (55mm I think). The 4.8is had 60mm pipes to the rear mufflers, again, hence the throatier sound. As an example, Supersprint makes one part number for the 3.0, 4.4, and 4,6is mufflers. They make a different part number for the 4.8is mufflers with bigger pipes. Eisenmann makes the same part number for 3.0 and 4.4 but different for 4.6is.

So the question is, if I were to find a cheap set of mufflers from a 4.8is, would they bolt onto my 4.6is resonator flanges? Or are the flanges on the 4.8is exhaust bigger than on my 4.6is resonator?