I got some extra power when I installed my 70mm mafs, but I think the biggest advantage from it is that it can let in more air. This is most noticeable if you have cams or especially an FI setup on your engine where you can really make use of the extra air the mafs will allow. Putting the two side by side shows just how small the stock unit is. It is one part of reducing restriction on the intake and on the exhaust-letting the engine breath better is always good.
2000ZX3 JRSC, 65mmtb, 70MM MAFS, modified Volant, JBA, Random tech, MBRP.