Last post for a few days:
We have a couple of customers with the header on their 06 WRX and they report fitment is just fine. Haven't had anyone with an 06 STi that I know of yet...but I don't think 06 STi fitment is any different than 06 WRX, but we report when I know for sure. I do know there are some folks with the "other brands" that have this style header on an 06 STi without the MadDad modifications(etg bung 45mm uppipe vs. 48mm) and there arn't any issues. Outside of the built in EGT bung on the manifold..it is the same as several other brands(built by the same factory).
whitson01 - your STi had a catless uppipe so I'd probably opt to put the money elsewhere but if I was looking to juice every last pony I'd got with the ScoobySport rather than the Flex...but again money is probably better spent elsewhere in your case.
Happy Holiday's gang. Hope Santa brings you an extra 50hp and a steering wheel for your Xbox 360(on my list)
, happy driving.....