By "turbulence", I think Jordan was getting at "pulse tuning" the exhaust pressure waves too maximize efficiency by degrees, since turbulence can never be eliminated entirely. Any
unnecessary exhaust restrictions, intersections, bends, and reductions in cross section will slow the flow by introducing greater turbulence which will ultimately reduce the volumetric efficiency.
Sources of turbulence that are inherent to a particular mani's design, like FP's (stock, Hafe, Evo III), typically use a shallow intersection for the merge collector just before entering the turbo with unequal length short runners. The FP design is conveniently packaged and casting sure helps keep production costs down, plus the reliability of cast manifolds is better than that of any similarly priced tubular manifold. Therefore, for most applications the FP is probably worth the trade-offs in ultimate performance.
By comparison the MAP mani uses larger diameter runners (significantly larger than used on a Full Race mani), which should raise the engine speed at which the max torque will occur. The longer primary runners should improve low-midrange power compared with an FP mani. Of course the cams, intake mani, porting, etc. will effect the pulse timing and the subsequent negative pressure wave, but no one said it was going to be easy!
