You will need to do a DPF delete at the least to get a worth while and audible difference in exhaust note for a 3.0 TDI.
I've seen others say otherwise, but I heard no difference at all when I did a muffler delete on my A5 3.0 TDI (2007). Saying that, 4" tips look real nice in my opinion and would go well with what you have there!