Are you talking about the manifold that has an aluminum runner? If so, that's what I have and I have my stock '98 heads. I haven't noticed any problems but my idle is a little rough. I think that just may be the fact that I have seven 9mm ignition wires and one 8mm stock ignition wire. (One of my FRPP wires broke so I replaced it with a stocker) And I probably need to replace my fuel filter too.
The hp gains are awesome. On my car I dyno'ed 211rwhp before and 226rwhp after. That 229 number came from putting my timing adjuster at 14 degrees. The real gains were above 4500 rpm. Up at 5500 rpm, I gained 25hp/25tq. It was awesome.
thats cool, I was wondering what you guys think about this. My car is a 1997, and ford recalled the intake on the car, while the car was not owned by me. Now the intake manifold does not have the aluminum piece on it. Here is what I was wondering, could I take my car to ford and instead of them replacing my manifold with a N.P.I. piece, could I as them for the P.I. intake manifold....is there a chance that this would work? Please tell me what you guys think