I contacted Magnaflow today and the only difference between part#15758 and #15759 is the location of one welded on exhaust hanger. They faxed me a blue print of both systems and the piping and resonator and the muffler are all identical part #'s. So you can transfer one system to another if you sell a vibe and upgrade to a vibe gt as I did. I had my catback on for a week and didn't want to lose money on another purchase. I hope this helps you all. Rick Dawson @ Magnaflow checked with the engineers and the exhaust will interchange without the extra hanger, but my exhaust shop will add the extra one since this is a $10.00 charge.