The more powerful the engine, the bigger the wastegate you need. This is one of the more popular misconceptions. Use this simple guide before setting out to find the biggest wastegate you can afford.
Big Turbo/Low Boost = Bigger Wastegate
Big Turbo/High Boost = Smaller Wastegate
Small Turbo/High Boost = Smaller Wastegate
Small Turbo/Low Boost = Bigger Wastegate
The larger the wastegate valve diameter, the bigger the flow.While the valve diameter is, without a doubt, an important part of the flow rate, equally important, but often misunderstood, is the importance of the valve travel. When comparing wastegates, don't be guided only by the valve size,check the amount of valve lift. In most cases it's more beneficial to have a wastegate with a smaller valve and long valve travel as this will give you a better control of your turbo resulting in a smoother boost curve.