shave off all eccess metal that you don't need. When i did mine, i shave everything, inside the intake, the center of the throttle body, the exhaust manifolds, anywhere that would restrict airflow. Shave the head, boost compression, i went 30thou, but you could go more if you wanted to. Have the whole head done, by a machine shop, cost me about 250, but it was better then new. Match all the gaskets to the openings, if the gasket doesn't cover the whole surface, shave the surface till it does. While your down there, strait pipe the exhuast. I put a hollowed out flowmaster right after the o2 sensor, then 2 1/2 inch pipe all the way back. It breaths like open headers and sounds pretty mean. I don't ever remember what else i did to the motor when we put it back together. The key is to make it breathe. These engines really need to breathe. My stock 325e is now faster then an E30is with just these simple things done. I'm pretty sure it's faster then my mom's e46 325 too. Close anyway.
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