I have an 08GSR intake turboback exhaust (no cat) and 3port boost control. When the car was tuned the rear O2 was not working, now if I replace that O2 is that going to effect the tune/performance of the car in any fashion? It runs fine as it is the only "issue" is the SES light from the o2. I work at a shop and scan it regularly to be on the safe side. Any help is appreciated.