Metal locking nut - M8 1.25 pitch
Turbo and gasket swaps can be a pain, so you want to make sure you do it once and it's not going to come undone again. You can't use normal nylon inserted locking nuts because of the heat involved so metal lock nuts are the answer. They provide a constant tension to ensure they don't come undone as a result of vibration and temperature changes
Having looked at a few different makes and types, we consider these to be the best and now have a stock of them in M8, which is the size needed for 200sx manifold to turbo and the turbo to elbow studs.