[HiFlow5 0]

I think my car runs too rich, cause of the fact I smell gas while the car is running and I get pretty bad gas mileage. I know my o/r h-pipe has a part to do with that, but do I need an adj. fuel pressure regulator with the mods I have? I've also noticed lately that my car bogs when the engine is cold and sometimes backfires under throttle. If I'm running too rich will that cause my O2's to go bad? The O2's I have now are about 1 year old with 10k miles on them, so I'm hoping I don't have to replace them again.
-Thanks