I really don't like that manifold. The runners are not equal length (if that was the goal - if you're going to make each runner go into one collector it should be). I also don't like the positioning of the turbo. A better design would either be a 'log' design with good pressure, or two 3>1 collectors that are equal lenth. That would keep the discharge from each bank of cylinders equal. The big thing with that one is that as the rpms get higher the pulses get quicker; if you have uneven runners like that then the turbo gets uneven pressure and heat making the boost inconsistent.
