350Z HR Y-pipe installed on a 2003 G35
#771
#775
This. I've shipped midpipes before via USPS and all you need to do is adequately wrap the pipe in bubble wrap and packing tape, taking care to wrap sharp edges. Shipping a y-pipe via USPS shouldn't cost more than maybe $25. The midpipes I've shipped out cost me no more than $18.
#779