I had an Apexi turbo (AX53B70 P25) on my RB25, it was great made good power (250rwkw at 18psi) and my tuner remarked that it was one of the most responsive turbos he had tuned. However as i found out to my detriment they do not like to be oversped being ceramic turbines they will crack, get unbalanced ang break the shaft, they are no where as bad as stock turbos and if you keep the boost under 20psi you will be laughing!