OK!, the verdict is in, I jacked up my car, and took a good look with a mock up and measurements I got from the guy selling the 1st muffler
5 1/2 center to center or 2 1/2 " between the ends approx. 4 1/2"shell
and it seems the stock muffler is about the same size as the dual in/out, there IS enough room be it tight to do exhaust out the one side providing I keep with the stock size tubes, 2.5" will not work ,however, using the duals as the X/H-pipe at the Y and eliminating the OEM muffler, the pipes will fit in the respective sides but the duals will hang about 1" - 2" lower than stock, so therefor I have come to the conclusion that I will buy this bumper http://www.andysautosport.com/
1st then get the normal duals, but my question still remains, use the Duals or just get 2 40s
1 more pic examples of the rear bumper http://www.andysautosport.com/ford/1999_2004_mustang/exterior/body_kits/kbd/kbdd01100224.html
2002 V6 Oxford White (Traded in for $5300 off the 2014)
2014 GT Ruby Red, planned 1st mod, MGW Shifter.
Biggest Pet peeve, People stealing the parking spot I'm waiting for.