^ I will concede that I come from gas turbos, and haven't had any experience with the VNT 15. I will trust that 2.5" is more than adequate, and it is quite large compared to stock, if you consider that. Plus as you implied ROR, not everyone wants their car to sound like that...
Yes stock turbo for now. Once I'm re-employed (laid off), I'll be getting a new DD and putting her under the knife.