So I've got a 97 2.5, about every 5000 miles the bolts on the exhaust manifold only on cylinder 4 come loose and cause an exhaust leak, the check engine light, and it makes a tapety noise (probably because its so close to the valves?) Anyway, I've been just retightening them every time and the problems go away for a few months. I was wondering if a new manifold would help fix this issue? If so what is a good one to buy? I know there are a lot of issues with the exhaust manifolds cracking and I don't want to buy one that will. Also a little extra performance wouldn't hurt, it is only a 2.5 after all. I was thinking of doing a whole exhaust system upgrade anyway. Header pipes, 2.5" tubing, high flow muffler, etc any systems to avoid?