i kinda noticed this too.. when installing the manifold, a few of the bolts are major PITAs to get on. i ended up having to use a combination of the bolts they sent and a few of the factory mani bolts if i remember correctly. and i did relocate the O2 Sensor to a slightly different spot to allow for my intercooler piping, but that issue only came up cuz i went with a different FMIC.