I'm in the middle of building my motor to support higher boost. I've been going back and forth on which turbo set up to go with, greddy td05 16g or Gt28rs to be in 550-600 wrhp range. When reading up on the searches I've found that greddy are great but pricey, the GT28rs seem to put good hp number and less costly. But I have not seen too many positive or detailed postings on the Gt28rs. If your running any of these turbo kits, all your technical feed back would be helpful.