I have the viper responder on my 03 Si and it is a good alarm but if you are in a show or in my case at work the remote range does't work at that distance. so the key pad wont vibrate or beep if you car is being messed with. thats why I put the viper 850 xv is still has the antenna in the window for long range remote function but you dont have to have that big remote
that A eats a battery a month B gets scratched very easy(no leather case)
C bangs around like crazy with my si stock suspention. it just makes you more worried and if you are ever out of the very limited range it does you no good. save the extra $200 from the 790 and get the 850 and spend the extra money on the prox sensor and the window module and the back up battery and interior siren. I ahad my install guy hide the alarm brain in a different location most thieves look under the dash at the steering wheel
where 99% of installers put the alarm brain. just put it in a different location that will help alot! I also have my horn and the alarm siren hooked up to go off so its really loud. I have lo-jack to and the brake lock.
sorry for rambling