my engine light came on 3 weeks ago. my psi3 says it was p0139 which was a cat i think.it went off but came back on today. so wot r the options? and money involved?can i just fit a cat bypass pipe? i want 2 increase the power soon so? i have an 04 wrx ppp sl with only an hks air filter as upgrades. also should i stop running it? as i am starting a new job this week and am gonna be using it 70 miles a day? help?