Cooling the intake charge can definitely add horsepower, but I don't know how much better we can do with our stock intercooler core. I think the best we can do is try to keep the core from getting heat soaked in the hopes of maintaining power. Once the IAT's start to go up, timing starts to get pulled.

Also, I definitely agree on the ignition and exhaust mods. Aside from maybe the manifolds, the AMG exhaust is already very efficient and stands to gain very little from modification. Our ignition system is a dual plug set-up and other than plug gap, there isn't really much room to improve (in my opinion).

There are definitely other things that I believe will make an improvement in power, but your list is a great foundation and probably the best bang for the buck to be had. Any additional mods are going to start adding less gain per dollar.