Sounds good.
I have a 2009, did you happen to note the color of the wires you tapped into? Also did you run the wire w/diode into the horn relay in the under hood fuse box? Since you used the door lock motor wiring when you hit the door locks inside the car while driving do your siren chirp?

 

I used the pink wire for the red wire and the blue for the black.

I made a DIY for it here as our cars are different than the 04-06 models. https://www.scionlife.com/forums/showthread.php?p=4062960

I did not wire it to the horn but used a siren from my wife's old car alarm. Yes it still makes the chirp when you press the lock buttons inside the car.

 

i cant find that 50v 6amp diode at any of my radioshacks.. i find a 50v 1amp diode, would that work fine?

 

That will work just fine.

 

thanks for this write up looking forward to hearing my horn honk with the locking