I wouldn't bother with hondata/tuning until you've done more to the motor. Header and cat *might* get you 5-10hp on a B16B, but prolly more like 3ish throughout most of the powerband. The stock B16B header is pretty well designed though, probably not worth the money.

Could save up for some upgraded cams and valvetrain:dunno: Thats the only way you'll make significant power without oxidizers or FI, short of a rebuild.