I recently scraped my old Greddy T78 and am now running a Sound Performance SP 74GTQ with a .81 exaust AR. This turbo is basically a Precission Turbo PT 74, but Sound Performance takes them and does some porting on the housings for more flow. The T78 is a 68mm compressor and a 1.0 exaust and this setup is a 74mm compressor and a .81 exaust. I havent had a chance to get it on the dyno so I have no new power numbers, hope to have that soon. The spool up is very nice. I havent tuned the car yet with this turbo so I have only been running 8psi but I see that at about 4,500rpm. So as far as I can tell spool up is very similar to the T78 with a much larger compressor so I hope to see a bit more power, But I am not expecting toomuch of a gain because of the smaller exaust side... Anyways, I havent been on here in a while so I just thought I would let everyone know what was up with my car.

 

Please post up the info when you get the info as im also looking into getting same turbo. Im looking at either the 74 or the 67 both with q trim.