So I recently got a used 2015 FiST an I kept reading as much as I could in these type of forums an I'm having a boost issue.. I feel as though I lose alot of top end boost at 4k, yesterday I took the front end off to find an inch of what looked like tar on both rads.. I cleaned them off, even tightened the hoses an still feel like I'm losing power somewhere.. anyone have this issue or know what I should do?