I'm planning on getting equal length headers for my 04 STi. Just want to know if it'll negatively affect my dyno tune. Any info or first-hand experience would be appreciated.

Thanks in advance.

 

if you had just the "stock headers" on before, then yes, i would recommend getting a tune.

Don't forget, it's not just the fact that they're EL and likely to "slightly shift the power band" around...

The primary collectors (?) going to the up-pipe are also probably different sized and will make the response of your turbo quite different. So, to avoid excessive lean/rich conditions, get the tune done.

Of course, I just might not know WTF i'm talking about...

My situation...
I was Stg 2 pro-tuned by GST to 263/297 HP/TQ, all i added was Tomei EL headers and got the re-tune...i got 287/320!!! That mod alone felt like my buddy's catless (but stock header/UP) setup...much more immediate response!

YRMV...

 

^what he said.