Turbonetics talks big but, I have yet to see any proof that they trample the GT series like they say. They might be comparable to GT series turbos. As huge as Garrett is and as much time, effort, money, engineering, and high tech equipment as they used to design the GT series, I have a hard time believing Turbonetics has come up with some new "revolutionary" stuff.
Just FYI, Precision Turbo and sever other turbo retailers/builders have done the drilled compressor housing anti-surge conversion for years. It's nothing new. These turbos look to me to be little more than some redesigned wheels with modded and painted compressor housings. I guess at this point it's all speculation until we see more people using the GT-K series.
'87 3.2 Carrera - 3.4l, Billet Design equal length headers & full bay IC, 60-1 T4 .81a/r, Kinesis Supercup replicas, Big Reds at all 4, 964 body conversion, 964 Turbo S rear spoiler