Pretty sure mine had the stock actuator on it. The response form the turbo was sensational, really good mid-top range with a huge whack at the top (for a small turbo). I was extremely happy with it and you cant complain for the price, great bang for bucks. Throttle Response was almost identical to stock, it takes a fraction longer to boost up to the full 20psi, just dont expect to floor it and WHAM instant 20psi, but after driving several other modified turbo cars and modded skylines i didnt even notice it after a few days. Having said that its still super responsive for street driving, which is why i had the GCG as most streets around me are 50km/hr zones so i didnt want any form of lag. Was very happy with it, and you will be too. GCG have a tip top reputation, and the reason i bought their high flow is many manyexperienced forum members couldnt say a bad word about them. So all in all thats my 2 cents and experience with those turbos.
ENJOY!