The only way you would find out for sure is to drive a GTR from both setups which for most people, including myself, is not possible. The next best thing would be to rely on the opinion of people you trust. Based on information that I have solicited on both turbos, the Apexi AX53B60 has no performance advantage over the HKS 2530 to warrant its higher price when purchased new. If anything, Tyndago has said that the 2530's have slightly more output than the Apexi's. I do know that generally speaking, second hand 2530's go for a HIGHER price than used Apexi's AX53B60's at Yahoo auction Japan and they generate much more frenetic bidding activity. You can't go wrong with either turbo for the GTR but for the above reasons, I bought the HKS 2530's. Just my opinion.