hi just bought a padlock alarm from Aldi for £7-99, i have put mine under the seat of the R1, when the bike is moved it gives out 110 decibels, really neat bit of kit you could also bolt it to your wheel. but i like the stealth aspect.and it beats those alarms you see advertised for £40 , so go out and buy one,

good idea, i seen them at my local Aldi, had a wierd type of key that i could lose and never replace

Is the key like a bar with little wedges cut out of it?

If so, that's a disc detainer lock - Stupidly hard to pick without the specially made tools (which are kinda expensive) and even then, it takes a lot of skill.

Extremely secure - Lockie can still cut you a new one if you need, though.

By contrast, I bought an 'über secure' chunky bar lock with my first bike chain.

It has a standard pin tumbler lock and even I can rake that open in less than 3 seconds