I'll try to get a sound clip for you Tonight or tomorrow. I have not dyno tested this exhaust as I was supposed to do that with the headers and downpipes at the BTRcc tune day in May.
As far as I know GT will stand behind their product. All of the pieces are branded with GTs logo. I will also send Matt a message with the name of the buyer to let him know that you are now the current owner and I'm sure he will take care of you.