I run 4 T162C RF coaxials in all the doors (i run coaxials cause im cheap), it runs off a T3002amp. I also have a T1 sub, and it runs off a T5002 amp. Do i need a equalizer. I dont know, because i dont know how it works.
As a general rule, if you don't know if you need an equilizer, you probably shouldn't get one. Anyway, equlizers are used to flatten your system frequency response. With a 2 decent sets of coaxials and a sub, its probably not necessary, depending on how picky you are about sq and having a flat response. However, you're probably running that sub in a ported enclosure, giving you a peak in your system's response at the frequency your box is tuned to. Some people like this, but if you wanted a flat response, a good equilizer, SPL meter, and a test cd could flatten that our or any other peaks or dips your system might have. Hope this helps.