I put a Prestige car alarm with keyless entry. I let a pro install it but it is one of the best improvements I have done to my 1988 190E 2.3. It is great not having to use the key to open and lock the doors. You will have to buy a special valve that will operate the vacuum lock system but it is only 15.00 to 20.00 bucks extra. If you need anymore info email me.