just bought an injen cai for the 04 sti, wondering if i should get the car tuned or if i will be fine without a tune. any information or opinions you have will be greatly appreciated.

http://forums.nasioc.com/forums/showthread.php?t=1395291

dont run it unless u want it to run lean and rich but protune diff story..

Diameter at the MAF on the Injen CAI is pretty close to stock if not dead on. I still have a bit of A/F correction I could tune out with mine but I never had any problems with mine with or without a tune. My o2's up top are actually a little rich compared to my map which is opposite what everyone would tell you to expect.

That being said, you have an 04 STI where as I have an 03 WRX with an 02 ECU, so my ECU is more forgiving on the whole.

Don't always believe the doom and gloom. Not every mod sold by a major manufacturer with at least some amount of R&D and testing involved is to be put onto a car with the sole purpose just to blow it up. The Injen CAI can be tuned for, but doing so isn't for performance, it's to put the flow numbers back to where they belong so the rest of the tuning can continue without an error.

/Brox

very well explanied