Ok, so recently I just put exhaust on my '98 Ex. I hollowed the cat., piped the rest 2 1/4", and have a silver bullet muffler. I also have 4-2-1 header, but my prob. is that my Down Stream O2 sensor is causing my check engine light to come on. I keep resetting it, but after a couple of days, it comes right back on. Is there anyway I can bypass this, or do something to keep the check engine light from coming on. Thanks!