I currently have a small buzzer attached to the gas cap wires so that on lock it makes a beeping noise. However it is very faint and the door locks themselves are louder. Could I swap out the small buzzer for this (or something like it):

http://www.motoringwerks.com/p-2418-...-horn-kit.aspx

 

You could if you don't care about being an annoyance to anyone unfortunate enough to be near your obnoxiously loud car.

 

guess i'm confused but wouldn't attaching a car horn make just that sound? a horn noise? like every other car alarm/door lock system in existence?

 

Yes, and they're annoying.

 

Can't this be done with coding?

 

No. You must have the alarm module installed as sounding the horn is hardware-dependent, in this case. Same with the heartbeat on top of the Tach (unlike the R56). Sorry.

Are you having difficulty telling when the doors are locked/unlocked? If so, you could have more of the car in your sight when you attempt to lock/unlock.

I'm just sayin'...

 

Why not just get a louder buzzer? 90db+ should be fine. Amazon or RadioShack should have them for under $10.
Recheck your wires to make sure you have them connected correctly. Mine makes a very week sound on the UNLOCK, just a side effect from the way Mini uses the wire to the gas door.

 

Boo lock beeps. That's my $0.02 But yea for mods