turbo should be the last thing you do to a N/A engine. build it up strong then at the end when all other options are done. you turbo charge the M***********.
Just be careful, you don't build up the NA engine with NA only parts, if you plan to go Force Induction. There are parts which are strictly for high performance NA engines and strictly for Turbo engines. If you get really aggressive NA cams, you'll probably just be wasting money cuz that won't help you much once you go turbo.
So, back to NA vs Turbo...
If you have a HP goal, with NA you'd have to rev the hell out of your engine to get that much power. What you get with turbo is tons more torque, and you don't have to rev that high to get your HP goal. Either way, if you want serious power both ways, it'll get real expensive real fast.