I have a test pipe that I havent installed yet because I want to find out if its okay to do so. It's 2.5", it has two holes for the o2 sensor. I drive an obdII integra ls. I was wondering if i need to plug up the other o2 sensor hole and would the computer be reading it as running too rich? Would I lose performance if the check light is on? Do I need the obdI to obdII connector? and is 2.5" be too big if i had dc 4-2-1 headers and 2 1/4 crush piping with stock muffler?