I have gone single for my track car,it is a lot easier to work on, actuators were sold ,Bought these off a mate who also gone single,sorry no receipt as I did not buy them from HKS dealer CJ Motors. I have also put a pair of 2530s replacing a T88-38GK to make one of my GTR33 street legal in Victoria.350kwaw on 98 pump fuel. The core is Garrett -5, 2530 has its own HKS housing which flow better.that the only difference