I had one installed yesterday. I was going to DIY, but I could not get the mid muffler off of the cat (should have been easy, but I tried like hell for almost 3 hours to no avail). Mid and rear mufflers. It's a 95 E320 wagon. It was pretty spendy (almost $1K), but I plan on owning this one 'till its junk, which shouldn't be for some time now. Although these mufflers apparently usually fit perfectly, the mechanic said he had to do a bit of bending of the midddle muffer pipes (the ones going into the cat were slightly off: I'm going to call Timevalve and let them know). They custom make each piece after you order it; they use a jig that they set up from an OEM as the template. The car sounds as quiet as ever, and I haven't driven it to check for noticeable power gains/losses.
1995 E320 wagon