1. There is no "speed quest" in designing BOV's and wastegates. BOV is active only during throttle liftoff and is kept shut during accelleration. It doesn't "provide speed" in any way. Unfortunately, it provides millions of youngsters a chance to dream about being one of characters in Fast and Hilarious when they drive around in their sneezing VW 1.8T's. When it comes to wastegate, it just opens a valve and let the gases go around the turbo. Albeit wastegate is more critical from material standpoint then BOV, I really don't think engine will notice if 40mm valve is OEM or Greddy or chinese copy or whatever. It's just a valve.
2. Installing harder spring in wastgate in order to raise the boost is not recomended. It's much better to keep OEM 0.7 bar spring and raise boost trough boost controller or T-orifice. That allows you to go back to stock setting if needed w/o tedious process of opening the wastegate and swapping the spring.
Thank you for your time,
Last edited by beepbeep; 02-02-2007 at 01:49 AM..