Like Stazi said...air-to-air are cheaper (or can be had for cheap)...plus I think everyone wants the look of an intercooler hanging out there...In fact have you seen those fake intercooler air -intake things?
My air to air work spretty well...(I wouldn't say better than the ADC) but good nonetheless. After driving, you can put your hand on it and it is quite cool, but after letting the car sit...it heats up b/c the turbo is rigt underneath...and I have an intercooler sprayer that I made. And for most the biggest drawback would be the hole I had to cut in my hood, but I actually like it. Mine is from a Saab...35 dollars...not bad.
