N55 twin turbo!

So the N55 is the single turbo engine that came after the N54 wich was a monster when tuned. So they removed one of the turbos and made a very reliable and cleaner running engine. Nice, or not so much. Since when tuned the N54 would make easilly over 50bhp over the N55. Now every performance N55 that is breaking the 400bhp barrier is a twin turbo like the M3/M4 and the Alpina. So how come there hasn't been a thread discussing this here? I mean there are ongoing big turbo projects going on but none working properly so far. So how come no one has been looking at this. The N55 is present throughout the entire BMW range.

So anyways I just wanted to start a little discussion on this. I'd love to hear what everybody think about this.