This turbo wheel upgrade compressor wheel also know as the wicked wheel. This wheel with performance modifications controls turbo surge problems associated with the stock turbo wheel. It fits the GTP38 stock turbocharger. The anti-surge wheel is a direct fit replacement and will enhance turbo performance when towing or adding horsepower with performance. This is the same wheel which comes factory on the 94-early 99 turbos, thus it will not change the characteristics of the turbo unless your factory wheel is damaged. It is ONLY an upgrade to the 99.5-03 turbos to reduce / eliminate turbo surge. Compressor surge is a phenomenon where the compressor cannot increase the pressure of the air it is pushing and results in the reversal flow of air through the compressor.