Intake question
 

i put an filter on my 90 na. should i have a mass air o2 sensor or is stock fine. is there any restrictions

it's fine

how can i get more air flow? besides getting the headlight cover with the opening ...can i relocate that little metal box behind the headlight on the passnger side and cut a large hole for better air flow???

You do know the Fc went on a major diet before production with every possible cost effective wieght saving done?

All that said, there must be a reason that steel is there. Cutting it out will probably compromise the body in the event of a collision there unless you beef up the metal surrounding the hole to compensate.

2x Post

...I cut a hole under the airbox, and put a filter in the fender...

I know, I had to make the stock hole behind the pass headlight bigger myself to fit my FMIC pipeing through, but I did rivet on a extra panel of 18 AWG sheet steel (with the wire and intercooler holes in it) there just in case.

Not sure how much it will help, but when I was shopping for a new FC back a couple years ago now, you would br surprised at the number of hacked up butchered up holes there were in that spot.