Bodies? Pfft. Go boost...
Without trying to sound biased here... ITB's are awesome! But, and this is important, I am very much a fan of NA and I decided to go down this route for the driving experience that such a setup would afford / provide me with. I wasn't chasing numbers (which are never going to be massive with NA tuning on these engines for reasons that have been pointed out elsewhere) but I was looking for an exciting and 'highly strung' nature to the drive; which is what I get. It's not cheap and, personally, I would look to get ITB's done along with some other supporting mod's (such as decent cams, valves, ECU, etc) and, of course, the mapping.
The biggest thing I tend to see / read is that people go down the ITB route with unrealistic expectations and, ultimately, become disappointed when they cannot catch their mate up in his or her Evo (a bit of a generalisation there, I know!) A well sorted ITB setup can result in a rapid and engaging drive (when pushing on) and a fantastic soundtrack, but it won't result in a properly fast car (like, say, a high-boost turbo setup would). It's all about reality and expectations and what you are looking for from the car.