? At what point do you need to...

Well, once you P&P the intake and add the upgraded MAF, it would be a good time. The CAI will help it breath...but not sure on the TB. You will probably see better throttle responce (from what people say), but not sure if its the best bang for the buck.

Different tuners will do different things to get you power. My tuner doesn't do much with n/a cars....he feels it's not worth bumping up the timing just to get a few extra hp. Same with supercharged cars....he tunes for safety.

So, I would get a tune by someone that has the experience, and isn't going to try to get you everly last hp by sacrificing your motors life.

The next set of mods should be on the exhaust side for you....
Good luck

Ditto that...you're already running premium gas, so there's not much more safe timing left if any. (GTs benefit from this)

One you get into porting the intake and adding an aftermarket MAF I would get a chip with dyno tuning to match the fuel to your new air flow.

with all that you have I would suggest a programmer instead of a chip....a chip is a one time deal while a programmer such as the predator may always be used update your computer if you are dissatisfied for any reason or you get something like a supercharger. Just my opinion