Are there any tuning options, like aems-4, that are worth spending money on? Or should I just spend the money on engine mods

 

You can only use a stand alone tuner and that requires a manual transmission.

 

Can you go into a little detail on the stand alone tuners?

 

You need to swap your trans before you can use one.

 

The Greddy E-manage blue is the only thing that has been proven to work with the autos. However, it has its limitations, the biggest being you can't advance timing which narrows its usefulness to FI. Like Dave said 6-speed swap and you can get a complete stand alone ECM that gives you full control.