Ok... let me clear other stuff up too. lol
The ITR motor does well too because of it's header, exhaust, and slightly larger diameter piping.
Everytime I see a stock ITR engine with some crappy aftermarket header, civic piping, and stock exhaust... I do this :smackself
This engine is already Pre-Tuned from the factory to be at it's peak performance at stock. When you start messing with bolt ons, you hurt the performance of the car unless you're very careful about the internals and bolt on you pick.
My buddy has an ITR engine in a EK Coupe and he's hardly any faster than stock GSR's and B16 Civics. He is faster, but not by much. He takes them way later and most of the way they're not too far apart.
Go with the GSR engine and you'll be happier in the end if you want to mod. With the extra money you can also spend on other parts and make it faster than the ITR engine.