Black96VertGT said:thanks. i have read that the 96-98 heads actually flow pretty well and they can outflow the pi heads at higher rpms. my understanding is that the main bottleneck on the 96-98s is the lower intake. swapping in a 99+ lower intake supposedly nets like 40 hp, mostly in the upper rpms.
NPI heads suck, plain and simple. Ported is another story, almost anything can be ported to flow better. Outflowing at higher RPMs but not lower ones makes absolutely no sense, and if it does that's a camshaft issue, not bare heads.