My first thought on reading this post is the same as any other race car I've built, performance street machine, or modded engine, and I think the other guys were trying to elude to this. What do you want the end result to be???
Do you want more overall power? Or do you want more bottom end? Do you want to roast a tire on demand? Or run from the pack down the highway? Race it or ride it?
Turbo: yes stock comp ratio of 9.5:1 is too high for effective (note not impossible, just not as efficient as it should be). Then with a turbo you Have to consider spool rates and where you want the power to come in, not to mention cam choice to match and programming that would have to follow. Is it a power band change you need? Just making it come in earlier or later could something simple like a sprocket chg work? (yes I know it doesnt equal the power of a turbo, but you get my meaning)
Air box: cold air is better for power, crap to warm an engine up on, and one of e things that makes cold air better is at it is denser therefore for maximum (note not 100% necessary as many will tell you) efficiency do you need to look at remapping the fuel curve to match? Similar story w/ pipes, what do you want the end result to be? This changes your power band based on different back pressures, flow etc. ( I do believe this was mentioned earlier but can't go get the quote on my iPad).
Like I've seen waaayyyy too many guys do, put 10k$ into a machine that they could have put half of that towards a better starting platform and not needed half of what's left over to get it to do what they wanted in the first place. That's not to say I don't appreciate modding and experimenting, hell I love it, love reading and seeing all about it. But ask yourself the hard question first "is there a better platform to start with that even if I held off for a year or two it would be worth it in the end.". If not then hey go for it, just make sure you do it right and do the research, starting here is a great idea.