alarm thing is personal preferrence. if it is indeed reputable one, anything also can.
cobra, clifford etc.
if you have a friend in hong kong (not sure if theirs is 240kmh guage cluster; try inquiring).
one thing you need to be certain is this----->
"All you need to make your car go beyond the 180kph japanese speed restrictor are the instrument cluster block and an ECU from a country which uses similar grade fuel, because of the*mapping software"
else it wont work correctly (because I know :( )
image from a friend
http://i3.photobucket.com/albums/y96/koolspyda/240guage.jpg