Well all the protege 2.0s had the vics manifold, I see them all the time in local yards and at work. Sadly the later 626s dont have this manifold. The throttlebody is oriented differently btw so re routing the intake ducting is needed.
Hooking the VICS up is simple enough with a window switch, the OEM method can change the opening/closing based on RPM and load also but the difference would be small.
As far as I know all the FS throttlebodies are the same size, I dont know of any simple method to instal a larger bore tb and besides I doubt it'll make any difference even with lots of boltons. Oh and you cant just swap the upper or lower portions as your stock manifold is one piece
As far as cams the only oe cams that are upgrades are the FP 1.8L cams or the mazda performance cams, both of those options only apply to the intake though cause neither have the distributor gear machined.
Other options are limited to regrinds starting at around $500 a set.
For the MAF the Millenia housing is larger and will fit the FS sensor (the sensors are likely calibrated differently as they have different part numbers) but there is doubt that this would work well or even at all.
Since you are increasing the ammount of air able to enter the motor but the sampling orifice is the same the reading sent to the computer will be different from what is actualy being flowed effectively leaning the motor out.
It might not be enough to endanger a NA motor but then if that were so it likely wouldnt offer much in gains either.
Iwould suggest carefull testing of the car stock then with the intact millenia sensor (it may not even run) then the FS sensor in the Milli housing.
A wide band would be critical here even for a NA motor.
Upgrade injectors are common for the FS as they use common bosch style top feed injectors, the most common step up are the 1G GT injectors. Early or late injectors will work fine but one type has different style connectors and requires splicing.
But Idoubt even a really heavily moded NA will require any upgrade at all, and if you find your self running out of fuel a pump and / or regulator should be first up.
Look into a standalone or piggyback system also, all these boltons are nice and should make the motor stronger but the stock ecu wont self tune for performance and dosnt offer much support for tuning externaly. Youwont see huge numbers for the investment but an ems will allow you to eventualy milk the motor for all it's got.
98 626 sway bar Altima rear sway bar links.
~Patrick~ 
