Is the 5" dpf back exhaust from Magnaflow worth the money. I talked to them today on the phone and he said it will produce about 46 more lb/ft and the truck won't sound any diffrent. I find it hard to believe any gains will be had with all the other restrictions upstream. Anyone change the exhaust and have any input good or bad, 5" with a 6" tip looks cool, just not $500 cool unless it works!?