I run Flowmaster Delta 50's after the x-pipe and they are right under my cab and I get nothing but compliments how quiet they are yet still sound like a performance exhaust unless you stand on it.  I also have the remote QTC electric cut-outs for fun..  whole system is 3".  I do have Dynamat and Dynaliner everywear but the 50's are right under the seat.  The system dumps out in front of the rear wheels.  I've had the 44's in a corvette and they were horrible and I had the 10's on a 5.4 and it was a trash can.. maybe give the Flow Delta 50's a chance.  I will say the are very big and heavy..