ok, i just put on a header and now. when hitting vtec , the car struggle, like something is blocking ....the car won't go.
checked with enough oil, try the new spark plug already...still nthing help..

 

well if the car struggle after you puts header on....you didnt hook something up right, or maybe you actually bought a really nice header and need to get her tuned....but i doubt it

you probably hooked something up wrong.....

 

how big is the exhaust?

 

sounds like ur mufflers not free flowing enough maybe? tell me it isnt stock..

 

Do you have an O2 sensor in your header? i've heard of some being in the header - but if it's messed up it might cause the car to struggle because the ecu will start to guess when it comes to A/F ratios.....just my 0.02cents