I got my sets of tweeters for my Legacy and Forester today. The Legacy's were easy. The only challenge was figuring out how to get the screws tightened.
Then I stepped over to the Forester. It literally took me 5 minutes. Here's how I did it.
Open the door, take off the corner cover. Here's a video:
The cover is connected to the door with the wire for the tweeters. You can screw around trying to get that little connector to pop out from it's little receptacle, but it's really hard. I ended up twisting a little bit and it broke free, breaking the little tab on the cover.

Back of the tweeter assembly. It comes in two pieces. You just kind of shove the tweeter into the cover. It snaps into place, but once it's snapped in, flex the cover inward, like I'm holding it in the picture. You'll hear one more CLICK and it's fully seated.

There's only one way to plug that harness in. . . .

Then just reverse the process of taking the cover off to put the tweeter back on.
I have to say, even though these tweets are not quite as big or impressive looking as the Legacy's, they sound great, and the improvement on the sound system is well worth the money. Definitely do this addition first before you get an aftermarket head unit, because once you get a real stereo in there, you'll wish you had the tweeters installed.
Then I stepped over to the Forester. It literally took me 5 minutes. Here's how I did it.
Open the door, take off the corner cover. Here's a video:
The cover is connected to the door with the wire for the tweeters. You can screw around trying to get that little connector to pop out from it's little receptacle, but it's really hard. I ended up twisting a little bit and it broke free, breaking the little tab on the cover.

Back of the tweeter assembly. It comes in two pieces. You just kind of shove the tweeter into the cover. It snaps into place, but once it's snapped in, flex the cover inward, like I'm holding it in the picture. You'll hear one more CLICK and it's fully seated.

There's only one way to plug that harness in. . . .

Then just reverse the process of taking the cover off to put the tweeter back on.
I have to say, even though these tweets are not quite as big or impressive looking as the Legacy's, they sound great, and the improvement on the sound system is well worth the money. Definitely do this addition first before you get an aftermarket head unit, because once you get a real stereo in there, you'll wish you had the tweeters installed.