I replaced my 881xp with the 990 and so far ive been very pleased. The hookups were the exact same so all i had to do for installation was swap the brain and windshield mount antenna. The only differences iin the equipment is the windshield mount antenna is about half the length as the 881, the remotes antenna is about a quarter of an inch longer, and it comes with a blue led instead of a red. The range however is the only difference i can find in performance. It is incredible compared to the 881xp. With the 881 i could be a few hundred feet in a parking lot with lots of other vehicles and it wouldnt reach. Now i can be in that same parking lot only about 700-800 feet away and inside of a building and it will reach no problem. I havent even been far enough away from my vehicle to where the remote wouldnt work. All in all a great security system with excellent range. If your worried about range this is definately the system for you.