Hmm that may be it, I bought the hex style bolts so we'll see if it fixes a possible exhaust leak, if the noise is still their ill look at the valve covers. Im like 95% sure the valve covers are fine, I checked to make sure they would clear the rockers before the heads went on, and they were fine, with the gasket it would have even more clearance. You can hear the noise, its kinda like mentioned before, sounds like 16 little sewing machines, but I think it could also be an exhaust leak just because the noise is LOUD at the passenger back of the header. So we'll see, ill keep you guys updated, I havent had time to change the bolts cause i have to let the car cool down, havent had a chance.