I have researched and researched many a forum about downs and ups when it comes to the ej20's pipes. And now i am just discovering headers for the 2 liter turbo engine,,,,,

Question: when i upgrade to my vf34 how much would a set of headers help my tunability, reliability, overall hrspwr?,.. Are headers necessary? cuz ther daaamn expensive thats for sure. I was also examining the pics of the invidia headers and i couldnt help but notice the censor ....uh....flanger??...idk whatever its called. hole? . . . . does any egt sensor just screw into this nubbin>

any info on headers would be helpful. thanks for your time people