Bought an Outlander 2 weeks ago here in Canada.  LS AWD model.  Base stereo is average at best.  Door speakers are simple 6 3/4 dual cones.  Decided to add tweeters in the upper part of the door behind the mirrors.  Pulled the triangular covers off and lo and behold - there is factory pre-wiring already there! 

Cut off the factory plugs and wired the tweeters as follows: Orange +, Brown -.

The right side has similar wiring.

I attached the tweeters to the back of the covers, snapped the covers back into place and presto - instant better sound. 

With tweeters in the doors, stereo imaging in the vehicle is greatly improved. 

I'm using a set of Pioneers that I had sitting around.  Best thing to do is go to the Crutchfield website and look up tweeters.   I had to physically cut some of the plastic surround from the speakers to make sure they fit well behind the factory panel.  Or, you could call your Mitsu dealer and ask about the factory tweeters.

Just installed the tweeters on Friday in the Outtie and the sound difference is dramatic..and the install was easy..the only thing is, be careful when replacing the covers, there is a little white holder that the top of the cover snaps into, and if you push too hard, it just gets pushed into the door panel, and you can not snap the cover back in place anymore. I just stuffed some tape in the hole and was able to secure the cover back on. This post was just to let the Outlander owners in the US know that the non-XLS models are pre-wired for tweeters.

Briansrt - if you take the lower front door speaker off (pop off the grill with a flat screwdriver, then unscrew the speaker from the door) and reach inside the door - you will be able to reach the little piece that fell into the door!

FYI