I found a way to attain high gain tones on garage band...
I was monkeying around in the studio with my programmer tonight and we stumbled upon this little trick. This is for all you garage band users who wanna get some balls out of garage band.
Here's how it goes:

Set up an amp sim and set it to your likings
Then set up a bass amp sim on the next effect and dial that in.
Next, download an AU called camel crusher. It sounds bad on it's own, but I set it to the tube channel and used it like a tube screamer.
For the last effect, add the bitcrusher and tweak it low-low mid on both settings.
It takes some effort, but with this combo of effects, you can get some monster tone (for a modeler of course)
Out here you've gotta know where your towel is!
If i can do this, i will keep it in mind. But thats a big if for me....
Thanks anyways. My drummer might know how to do all of this.
-Andrew H
band: syncopated groove punch
it's really easy, add the guitar as a real instrument, click on details, start adding the effects, the only one you need to download is the camel crusher, the rest are right in there
Out here you've gotta know where your towel is!