18 psi on stock turbos is too much. I know it's tempting but unless you want to spend thousands rebuilding your engine turn it down. I would also seek more advice on the high boost when your EBC is off. I asked about the turbos and wastegates and didn't get a response. If you are all stock you are causing damage by running those turbos at 18 psi. The heat coming out of those turbos, especially with stock intercoolers, is so hot your killing your engine and turbos. I barely risk 18 lbs with Garrett T28's and bigger intercoolers.
Figure out the high boost issue and the hesitation at the very least or plan on an engine rebuild.
About the hesitation if it's over 6k RPMs then it's normal for your boost to drop off a little as you approach redline. Is the engine stumbling or what? Elaborate or post a video so we can give more feedback.
