Hi there, & welcome to the forum.
More information on the alarm please. I've seen them on other bikes, (not GZs) as factory fitted items, but not ones that are aftermarket. I'd like to fit one, as someone broke into my luggage box, in our underground parking, a while back,but I've never seen DIY bike alarms.
BTW Nearly EVERYTHING coming into Spain at the moment is Chinese. Stuff made elsewhere in the world costs $$$$$$$$$
whereas Chinese stuff is nickels & dimes. I mean electric drills for the equivalent of $10, bench grinders for $15. How do they do it? I know the quality isn't A1, but it's perfectly acceptable.
Apart from the bikes, that is. I bought a Lanvertti a couple of years ago. I had so many problems with it in the first couple of months that the dealer gave me my money back, & I put the extra down & got my GZ. :2tup: