I installed the rs3200+ kit in my '02 with keyless entry and it was a simple plug and play. just take your time and follow the directions step by step and should be no prob - the plugs would only fit into the harness one way, and each plug was different. the most difficult step i had was bolting the brain up under the center section of the dash
Aftermarket alarms will have more way more features/options, but i too was worried about hacking into the wiring after hearing stories. the rs3200+ is a basic alarm but the nice thing is it lets you keep your factory remote.