So I just ebay searched MX6 FSDE Header, and see a bunch of 4-2-1's and as long as egr bung is angled correct (parallel to ground right?) and for an FSDE, it should mount up to the piping? Or will piping need to be modified too?
yes, the egr bung should be parallel and your stock exhaust piping will have to be modified since the header is longer.