110% is still meant to use a O2 sensor "race header" doesnt mean a 4-1 or tri-y header etc , its going to have a hole with a nut in it somewhere like this that is for the sensor , if not go to the parts store and get a $0.25c O2 sensor bung and drill a hole for it after the collector and weld it on and run a sensor, the ECU needs it to make corrections on the engine , as far as the vtec goes id be checking the sensor itself and or the screen inside it , its based on oil pressure and IIRC if obd0 or obd1 it wont work if the computer is throwing certain trouble codes , aside from that Welcome To HondaSwap ! post some pictures of your ride , a eg hatch with a h22 should be ballsy