I've owned two of these exhaust, and I've been really happy with them.
My first one had a flowmaster and sounded like this (with cat-less Y-pipe):
http://storm.prohosting.com/cougarv6/yodude_f.wav My second one had a Dynomax Ultra Flo (also no cat, and MSDS headers, y-pipe):
http://odin.prohosting.com/~cougrrr/ultra_flo2.wav
You will find many, many opinions of this exhaust on NECO (most of which are very positive).
