Hi Magnuman,
I just did the same thing - trying to reduce the battery draw. After I removed the siren and fixed a short in my aftermarket alarm system, the quiescent draw (i.e., after the computers have gone to sleep) was down to ~30mA (0.030 amps) from around 0.25 amps. Less than 50mA is considered good. At a drain rate of 30mA your battery voltage will drop to around 10V in about 25 days which is probably too low to start the car (the calculation was done assuming a 48 amp hour battery capacity and 12V initial charge). So, if you plan on leaving the car parked for more than a month, either disconnect the battery or get a trickle charger. I use the cheap 1W solar charger from Harbor Freight.
Hope that helps.
-Jerry