"These HKS custom turbocharger units are Garrett based turbos that are designed and built specifically for the performance oriented. From the HKS specific compressor and turbine wheels and blade designs to the thier unique housings, each HKS Signature and GT ball-bearing turbocharger unit is race proven and engineered with the highest standards in performance, function & reliability. These units can be utilized in certain bolt-on applications or custom applications from the basic street car to a full race setups."
The internals are modified by HKS as well as the housings, although they look similar they are very different. Supraforums are always very biased on HKS stuff as the forum is run by boostlogic.