You should net more power with ITB's, no matter the build, as long as the fuel can keep up with it...but for most classes in [road] racing they aren't legal. As for tuning, any shop with a dyno can do it and you can with a "standalone" yourself too once a good solid baseline has been established. The main problem is constant tuning is required depending on weather (to get the most out of them), you will smell like gas, etc.

For the price a high quality header and an elephantitus password jdm/j's racing intake will have just has much gain with zero disadvantages.