I've got the 690vx, similar not quite as wonderful as 791....but the remote and range is the same. it lacks the remote start, and doesnt come with some of the extra modules. I installed mine myself. Was really easy I thought, compared to trying to install those
ebay alarms, which dont come with "directions".
Anyway I'm really happy with it. Randomly though.....and this doesnt happen to much, but I swear my remote picks up some other signal which sometimes sets it off (the remote not the alarm)....it'll start singing its little song, I'll flip out, run outside, and my car is fine.....its even done it when I was driving in a parking garage.
I've had it installed for about 6 months now....no problems at all actually. It was time consuming to install it, for me about 4.5-5 hours, but I had to take a lot of stuff off in my car (dash, center console...to access the screws to take off the dash). All in all I was very pleased with the results. I got the alarm on hooked on tronics for a good deal. $140, I'll watch out for price drops on the 551T (or whatever model it is) for the remote start to add onto my alarm.
As for passive mode(in the install manual for the 690, probably the same for the 791),
One chip means on, two chips means off
the passive arming feature is feature # 1(basic menu)-option 7
1. Open a door
2. Turn the ignition on, then back off.
3. Hold down the valet switch for "3" seconds. The alarm will chirp once (indicating entry to the basic menu), release the valet switch.
4. Select a feature. Press and release the button 7 times. THen press and hold until alarm chips...7 times. Keep holding!
5. Activate the feature on and off using your remote lock button, unlock will disable the feature.
6. release the valet switch