Swapped out my stock meep meep horn for the Hella horns someone else did a while back. The new horns are low and loud!! Just the decibal increase alone is HUGE. Sounds like a horn from a BMW, Infiniti, Audi, etc, etc. Some things I noticed when doing the install:
1. All you need to do to access the horns are to remove the plastic clips, in order to remove the plastic shroud above the front grille area within the engine bay area. Then just a 12mm bolt to remove the original horn. That's it.
2. The horns will not work if not bolted onto the car since they need to be grounded. I almost gave up installing the new horns thinking they didn't work until I realized this...
3. The original straight body color painted bracket the OEM horn is mounted on is needed when mounting two dual tone Hella horns in the same place since the stock plastic airbox funnel thing mounted above needs the clearance.
4. I've noticed some people have drilled a hole on the other side of the engine bay, in order to mount the second horn, but this would require significantly more effort to mount the horns this way. I just mounted both horns using the original 12mm bolt from the oem horn in the same place. You can barely see the new horns from the front in person. The original horn was visible in the same spot, so things were never visually symmetrical anyway from the front.
If you want to do a quick modification to your horns, it's an easy 15 minute job and about $45 in parts from Amazon. You just need the Toyota Hella horns and Toyota specific wiring splitter harness that connects to where you unclip the original horn. The other end of the wiring harness then is split and connects directly to each horn with the Toyota specific clip built onto the Hella horns. Easy as that. Oh, I also just zip tied the slack in the wiring harness cables to the mounting brackets built onto the horns. Works great!