Does anyone have any experience with the KYN exhausts sold on Amazon for $135?  I was looking at a black widow from the UK, however it appears the KYN and the widow are both made from 304 stainless steel aluminum.  Is this a deal, because its unbranded?  Love to get some feedback from anyone out there who is running one of these slip-ons.  

304 is a low grade stainless and certainly not aluminium, maybe it's made from 304 AND aluminium.
My experience with cheap ass exhausts it that they get hot and burn the damper material, sometimes they have a nice sound but that disappears with the damper material and end up sounding like the tin-man from the Wizard of Oz with a cold.