Clifford Products

Does anyone have experience with the Clifford intake manifold and headers? I read the threads about the internal engine components but I don't recall seeing anything about the intake and headers.
Does anyone have any experience with the Offenhauser manifold and split flange headers? I was watching Powernation the other day. They had to grind the intake manifold so it would fit flush with the header flange. Summit Racing says the intake is for use with the stock exhaust only. If that's the case, will it also bolt to the exhaust manifold like the stock intake? Thanks.