Nice looking ride...
Not too sure about that 24hp gain from the CAI and exhaust..our cars don't respond to bolt ons like the 05+ do. But if you dynoed the car and made those gains then I'll shut up
If you plan on a turbo then you'll probably want to hold off on any more exhaust mods...based on the turbo setup you might have to modify or change your current setup, so there's no point in adding midpipes, headers etc.
You'd also want your cam to be profiled for a turbo/FI setup. A cam with a lesser duration similar to an N/A car is what you'd want to properly match the lowered velocity from the increased pressure, oxygen and fuel density. Expect to pay at least $300 for a decent cam, plus you'll need upgraded valve springs at a minimum, which run a couple hundred bucks...as said if you aren't installing yourself you have to account for labor, which will be significant.
As far as tuners...the big changes to shifting/firmness is strictly regarding the slushbox autos...you will probably see some gains ~10rwhp 12 tq from a mild tune and also have the ability to adjust for gear/tire changes, raise speed/rev limiters and clear any codes.
Gears are a great bang for you buck mod but they do require professional installation...it's worthwhile to pick up a traction lok differential to install at the same time. ~200 for the tlok and 150-200 for the gears...plus 300-500 for install and other misc costs such as rebuild kits and oil/friction modifier.