This qustion has been asked a million times. You can determine your version
here. For future questions try using the search botton. Chances are your quation has been asked before. If you have a v4 or below, I wouldn't mod it. v1-v4 had terrible lasers which can lead to backup playing problems. If you want the best mod, get a Messiah 2. You can buy one from charlie_ps2 or dust2dust. Just send them an email to let them know you are interested and they will send you the details. Install guides are available at
www.messiah2.com