DPF-back on D3

I own C30 2012 D3. I would like to improve sound but keep the DPF and I heard 2 things:

1. DPF back (small muflers or just pipe) will improve the sound
2. No way to improve the sound without removing DPF

I know some people with older D5 did DPF-back and got nice results, but DPF in D5 and newer D3 is different (not sure if DPF in D3 is blocking sound more then the older DPFs).
Did anyone here (or knows someone) did DPF-back on D3 and saw some improvement? I am not looking for too much.. just deeper, maybe a bit more powerful sound, specially in low rpms when in idle/slow cruise to eliminate tractory sound of the engine.