I upgraded the front speakers in my '05. They sound pretty good if I lean my head forward and down. Obviously the speakers aren't aimed optimally.

What is the best way to "aim" speakers?

The only way I can think of would be to use rubber grommets/washers between the doorpanel and the speaker at the attachment points.

 

You can always sell those and get componets with the tweeter in the upper stock tweeter hole. Sounds much better.

 

A truck environment is a terrible place to tune an audio system because of hard surfaces, angled surfaces, etc. The only way is by trial and error. People sometimes spend hours setting up a single side of a component set. And, the user's preference is going to be different in every case. There is no perfect, generic way to do it. But, aiming frequencies above 2000hz at the listener is a place to start.

 

I'm just talking about physically moving the speaker so it's "pointing" in a different direction than the stock position.

 

My Infinity Reference 5x7's have tweeters that can rotate 360 degrees so you can point them where you want them. You might consider those. I got mine from Crutchfield. And they come with a easy installation wiring harness that connects to your existing OEM speaker wire straight to the speaker.

 

Unless you have components you will be very limited as to what you can do. As you mentioned, you could use spacers behind the speakers to "angle" it to a small degree, but how much you can actually move the speaker will be very minimal. But sometimes minimal tweeks have some positive audible effect. That's why it takes a lot of time to do tweeks such as this. Every little gain is a payoff for the time invested. It can be very frustrating. Sometimes you will take steps in reverse, as far as positive results. So be prepared. People who are impatient and like to cut corners are likely to not do well at this sort of thing. Like I said before, it can take hours for one speaker location.