All catless downpipes will sound more or less the same. What you're paying for is the fitment and the quality of construction.
Originally Posted by kiwi29
I've heard ar catless downpipes on a stock exhaust and I've gotta say... its extremely raspy and not exactly a great sound, a buddy of mine had them on his car and it was louuuudddddd. The rasp is similar to a e46 m straight piped (if you are familiar with how that sounds)
They are probably hitting each other and that is causing some rattling sound. Properly installed downpipes are not raspy.