I ordered the last GP set up Simon had on hand back in December... USPS lost said last set somewhere in the last 1.9 mile stretch from the post office and my house... still dealing with trying to get my money back.
Sorry dude, this is very similar to the issues I had when buying from Simon. Simon was fantastic and offered to refund my money no questions asked. USPS lost the package after leaving customs and it was never seen again. I called USPS and finally tracked down someone who gave a damn and found my exhaust at the local post office in the corner. I gave her the box dimensions, photos of the product, Simon sent me photos of the boxed product, and they started opening boxes. They found it, but it took 8 weeks or so after I started the claim with USPS. I was told the issue was that the label came off. I passed this on to Simon. Keep hammering USPS, hopefully they will care enough to find your exhaust.