An X-pipe will make a huge difference.. I know mine did. I have an X-pipe and Magnaflows and am really happy with how it sounds... no drone, no rasp or blumpy idle... just clean, smooth sound until you open it up.
How thick is the seat material? It might be worth adding material there and see what happens. It take less than an hour. You might be able to get scraps dense 40 oz. fiber cushion from a local flooring retailer. It's much denser than the factory carpet pad.
I have a H pipe but it was installed with the system so no comparison. Seat of the pants says an X pipe would be beneficial.
The x-pipe will really help with the sound. Im not sure if the placement of the mufflers is going to fix your interior drone your getting. you may have to swap to a different brand of muffler
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
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