On top of my head, the new Boomgear SS exhaust for i4 (V5, I believe) has the following benefit:
1) Reduce weight
2) Larger diameter for better flow
3) Fully heat-shielded
4) OEM valve relocation
5) Much better sound/tone than a Ti exhaust (ask
@TFS, he ride with me yesterday)
6) OEM style muffler but thinner and narrower (better acoustic balance and quiet when in close-valve mode)
7) Straight pipe performance when in open-valve mode
8) End tubes are fully inserted into the OEM tips for maximum output through the back of the car