I replaced all but one of thoes little gray and black in line check valves. Two of them didint look good but i decided to just replace them all. The only one that I havent done is the one located right under the intake manafold. Did anybody change this? Is there an easyer way then to remove the manafold? I was also wondering if anybody replaced any vaccum and boost lines with silicone or braded lines? If so Does the IDneed to be thesame size as oe? Thanks.........