I have seen / heard a 3.6 tdv8 with rear box delete and they sound nice.
The question is has anyone done it with the 4.4 ?

Don’t waste your time sir... The 3.6 does not have a DPF etc etc that mute the 4.4...

In short, a few customers have tried it and the 4.4 even with the complete exhaust (from the DPF back) removed does NOT sound and louder than stock! The exact same thing happens with the 3.0...

Even if you remove the DPF or/and the cat, the 4.4 sounds more like a helicopter jet engine...

So, i own a 3.6 322 with an Overfinch exhaust system and yes it sounds like a tuned V8... You won’t/can’t do the same or even close with the 4.4 engine...

i echo the above although on the 7 series engine version , mine never sounded like a proper V8 , I guess its like my saab 2.8v6 , it doesn't sound like a V6 due to the design of the intake manifold , its flat and for some reason quells that lovely noise the V6 motor should make

Found this on youtube, sounds a bit better.