How high was your compression? I had 175 on all 4 and had to use 92 octane to reduce pinging. It's been running great for over 2 years. My guess would be the head gasket you used. I have been doing good with felpro.You guys mentioned a head gasket shim before and my compression was pretty high so I am wondering if it may make sense to use one this time. Do you recommend using one? I do not know the exact amount the machine shop took off the top of the block when they decked it. If I do use one does reduce the life of the HG or have any other negative effect? What sealant do you use between the block and the shim?