Which is a better choice:

94000 series (94006) - http://www.car-sound.com/02product/universal/940.asp

94100 series (94106) - http://www.car-sound.com/02product/universal/941.asp

i have the high flow stainless cat 2 1/2 in and out no 54306

It looks like the difference is the length. I'd get the longer one probably and avoid the inevitable P0420 code for insufficient catalyst. Without an Aeroforce to clear the code, it would be a bit of a hassle seeing as my 94009 trips that code about 2-3 times a week after the car warms up. You should probably get an Aeroforce anyways.

i know mine is half the size of the stock one and never got a code so far

You're not blown...

Good call. How long is the stock CAT? I'm not measuring in this crappy rain.

one thing to not forget i sold my old cat 70$ don't throw it away

Little update:

I called up my local exhaust shop and the "expert" said he used to use the 94000 series (94006'*) on 3800 GM'*, but it would cause the SES to come on. He said he called Magnaflow about this and they told him that it was a design issue with the rear o2 sensor so they redesigned it as the 94806. Ok fine, but look at this fugly thing: http://www.car-sound.com/02product/universal/948.asp

Looks bizarre, but I was told by my dealer that Magnaflow directly told him this is the part to use according to the updated catalog.

So, has anyone used this CAT or has anything to report of an SES light with a 9400x/9410x?

lol, wow that is ugly.

lol, that thing is hideous

if you get an intense pcm, you can get the rear o2 sensor deleted.... i think there are other things that you can do too...