I use a Audi TT 8J 3.2L exhaust for my V6.
From the exhaust headers I take 50mm = 2" pipes an make an Y-Pipe to a 70mm 2,75" cat and go further on with 2,75" up to the Audi muffler.
The end pipes I take only two 90° 2,75" pipes.
Original Audi mufller sound not good, like a electro machine, but I optimise it a little bit, inside the muffler there are two inner pipes and I close them with a steal plate. Now it sound very good but not extrem loud, very comfortable.
But it makes very hard vibrations under the car, or if you stand at a wall. If you go under the running car you must close your ears.
The complete system is very light wheigt:
2x V6 headers = 6kg
first pipe include cat = 6kg
TT exhaust include pipe to cat = 15,3kg
Now I will optimize it much more, I will close the inner tubes with a thin pipe.
Stay tuned.
