I recently bought a japanese import STR 2004, and I now learn it has not got an alarm or passive interior sensors, would it be possible to get the bits to comlete a standrd Jagaur alarm system to it, any idears ? would the wiring be in place ?

 

Mine is ex Japan also . It did not have the alarm activated from factory either.
Nor does it have the interior sensors.
I had to activate the alarm via the Jaguar IDS diagnostics computer.
The interior sensors are not necessary it works fine.
I have since turned off the audible locking and unlocking as it is damn annoying.
try disconnecting your battery for a minute then reconnecting the battery , without inserting the key and see what happens.
It may surprise you.