troJan4j

For the intensity
I believe you'd have to find the cars headlights in the carcols.ymt and change it there, however that would change the value for the car's headlights as a whole For the flash pattern
Look at the attached picture. At the top of the carcols entry for the vehicle in question, you'll see these sequencer values. For mine, in this pic, they're all at 0 meaning the headlights won't flash at all with the sirens. Simply create a 32 bit integer (i.e. "10101010101010101010101010101010") and convert it to decimal form and replace that number. This site will do it and even gives you a neat visualization of the flashing (everywhere there's a one) http://www.binaryconvert.com/result_signed_int.html?hexadecimal=AAAAAAAA