2003 ford 6.0 diesel 4 exhaust with cat and muffler it sounds like a jet plane all the time how would you quiet turbo sound down?

Install acoustical insulation and sound absorbing materials - Add damping material to the cabin's interior floor and behind trim pieces. These materials can help to absorb and dampen sound that could reach levels of 15 to 25 dB. If you choose to use this method, choose a material that will stay adhered properly to the surfaces over time.

Install a turbo silencer.

A turbo silencer is a device that can be installed in the exhaust system of a diesel engine to reduce the noise level of the turbocharger. Turbo silencers work by baffling the sound waves produced by the turbocharger, reducing their amplitude and making them less noticeable. There are a variety of different turbo silencers available, so you can choose one that best suits your needs and budget.

Upgrade your exhaust system.

If you have a stock exhaust system, upgrading to a performance exhaust system can help to reduce turbo noise. Performance exhaust systems are designed to improve the flow of exhaust gases out of the engine, which can help to reduce the noise level of the turbocharger. When choosing a performance exhaust system, look for one that is specifically designed for your vehicle and engine.

Sound deadening blanket- A sound deadening blanket can be placed between the engine and the firewall. This will help to absorb any vibrations and noise coming from the engine. There are different thicknesses of sound deadening blankets available to provide varying levels of noise reduction.

Reduce the exhaust tip size- An exhaust tip that is too large can create excessive resonance and noise. Reducing the size of the exhaust tip can help to reduce the overall sound levels.