Here's a pic of a turbocharged 4AGE. Raymond's. 1.0bar
http://i6.photobucket.com/albums/y242/sylkhannaz/4agte.jpg
But, 20V would be a lot harder. It would cost around 7-8K and i dont think the boost can go up to 1bar. 06++ maybe. Raymond offered to turbocharge my bt but i guess i'm too slow of a driver, like snail one.
U will lose VVT as it draws out raw power but possible if u slap in Microtech. The owner of that car (in image) done a number of turbocharged 4AGE, svt, bt. Should you need to know more, i can give you his phone number.