Looking for advice, BB headers vs. HP manifolds
When I ran HP manifolds in my car I had custom 3 inch head pipes built that cleared everything. They worked great for 20 years. Even had bungs for O2 sensors in each head pipe. These cost a lot of money since the flanges were 1/2 thick stainless steel and the piper were all hand cut mandrel bends, but that is what you have to do to have it last.
When I ran HP manifolds in my car I had custom 3 inch head pipes built that cleared everything. They worked great for 20 years. Even had bungs for O2 sensors in each head pipe. These cost a lot of money since the flanges were 1/2 thick stainless steel and the piper were all hand cut mandrel bends, but that is what you have to do to have it last.
