I install headers, test pipe and exhaust system in my 97 ex coupe, but is not running like when it was stock it just to run better before when it was stock but now i don't know why is not running better!!!

 

Because you are trying to turn an economy car in to a racecar that's why.You pretty much just killed what little low-end torque you had with those bolt-ons. That's why everybody says to leave these engines stock.

 

Ok so what i have to do to my car then???

 

put it back to stock