I have an intermittent noise at starting too. It hasn't done it for a while and it's been cold here in Upstate NY. My cousin told me it might be the starter solenoid. I didn't question him further - I should have - but I think it might be the solenoid not "retracting" and remaining in contact...
Good info! Agree on the plug n lay comment. I think there are actually TWO horns on the Tacoma (a low note and a high note). I can't imagine I'm the first to ever consider doing this.
I have a 2010 Corolla S - I also have a 2001 Tacoma SR5. I like the Tacoma's horn much more than the Corolla's. Has anyone here replaced or somehow modified their Corolla horn to make it louder with a deeper tone?