Your going to need them. I have a 98' with the 1.5 Z5 (wish I had the 1.8 ) I've never really messed with this car, one question is are you installing a ram air intake (short) or are you installing a true cold air intake that runs under your car? Reason I ask is CAI's tend to suck up water when you go over deep puddles, I've seen a K20 and a B16 both fall to this "irresponsible" placement of the pipe. Well one of the sensors (plug with 4 wires) goes to your MAF, you could retro fit this to the end of your intake pipe with clamps and silicon or equivlent couplers. The one plug with (2) wires I believe goes to your air intake temp sensor, you do need this. You can make a nice intake box out of thin metal, screws, 90 degree metal tabs and some metal tape. Then you can drill a hole in it for that sensor. If you do not plan on making a intake box then you should not bother with that mod. Just adding that intake pipe will not give you any noticeable difference in HP, it will just sound deeper. Go to
msprotege.com and search the site for "air intake" and you will get every answer you need.