How to make a Ford F450 louder?

The thing is quiet as **** for a 6.7 L Diesel engine putting out 440HP. I know this isn't a cummins engine and that one of the main reasons it's a lot quieter is because of the electronic fuel pump they use, but how can I make the engine roar, even at lower RPMs?

I don't want to take off the Cad. Converter, will consider getting a new exhaust.

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