One of my friends has a 2000 civic ex with the y8. It has an fpr, dc header, thermal exhaust, and an aem. It has a 5 codes, misfire on cyl 1, cyl2, cyl 3, cyl 4, and a random code for all cylinders misifiring. WTF can cause this? He is thinking its his coil, which sounds like it could be right. What else can we look into and how do we test this?