I dunno then. Both me and my gf can hear a huge difference in the car w/ windows up.

Under "normal" driving I cannot tell a difference. However, when I was backing up near a retaining wall I could definitely hear a difference. In fact, the sound resonated in the cabin as it bounced off the wall - before this "mod" it would not make this type of sound. (This retaining wall is part of my townhome complex.)

Also, when my tire was being replace today I could hear a difference when they were driving my X3 into the service bay. I was standing about 15 feet away from it.

I'm still going to slap in a Magnaflow muffler or Remus exhaust sooner than later. ;)

Little more time with this mod. I can hear a difference in the cabin between 1,400 rpm and 2,000 rpm at slow speeds. :cool:

I've noticed the exact same thing. I haven't told my wife about it, and she hasn't noticed a difference. I can tell for sure.

Did this Mod to my truck as well, and it sounds great. I am just concerned if it has any adverse effects due to the lack of back pressure at low RPMs. Does anyone have an answer on this?

ab did this mod last year, i noticed the sound the first time i started it
ab also said his butt meter noticed "a small decrease in low end performance"

I dunno, mine seems just as quick after the mod.

The only thing that I have noticed after doing this mod is the sound has more of a growl between 2000-3000 rpm's. My original question is does it hurt anything by doing this?

I don't think so. How can allowing more exhaust to flow out hurt the car? If anything restrictin gthe exhaut flow will do more damage. i.e. engine have to work harder to push the exhaust out = bad mpg. Also, alot and I mean alot of people have done it to their E46 and I haven't heard a single problem yet.