enigma, i suggested aam because thats what ive always had the most success with. ive been through 4 different intake manifolds on my z since it went turbo'd, no manifold has come close to the power that my custom ported oem w/ aam spacer made. since im going ls1 turbo in that z, my track car z is getting that same manifold passed down to it.
cginev, im not looking to increase power in my m at all, but im adding bolt ons to help the car breathe a little better (extra power is just a plus). with the intake, and spacer ive seen 2 mpg average increase. also with the spacer i help the front 2 cylinders from starving for air (if you look the front is angled down). by adding the spacer you increase air flow to the 2 front starving cylinders, which was a poor design in the z/g/fx/m vq35. and lastly a catch can and pcv mod to eliminate oil from getting into the manifold. (if you take off the top part of your manifold on a stock engine, guarantee youll find oil in the lower collector)