That is why you build it properly and you arent high compression. If thats a goal of yours you didnt mention it so he cannot assume anything beyond what you have stated. His suggestion is viable.
Read the replies in this thread relating to turbo with or without high comp.
http://www.clubintegra.com/board/showthread.php?t=79235&page=4
I havent even searched anything regarding b20's yet ive come across dozens of information regarding your question so i dont know how you couldnt find it. Whether its b18b, b18c, or b20, the general answer is all the same. All you can do is basic bolt ons without messing around internally anywhere (top or bottom). Force induction is the only way to bolt on more power after that.
You also cannot have cold air and short ram but you can build a short ram that utilizes cold air. Just trying to decipher what it is you have or confirm this is what you mean.
Another short answer would be a better intake, header and exhaust.