Wow, you really think 40lbs weigh savings? I know the axle backs weight a ton, but I didn't notice any difference putting in my magnaflow over axles, catbacks. If you can get some official weight that would be awesome, I'll put it in my spreadsheet.
2012 Black V6 Coupe Auto 2.73
BAMA 93+ Race Tune, Magnaflow Comps, 3370lbs
SVT Drift 18", Nitto NT555