LOOSE EXHAUST MANIFOLD: What is the secret to keeping a 5ktq manifold on tight? Tightened mine 2 months ago....now loose again, noizy! is it longer studs with double nuts? is it longer studs with sleeve and nut a la SAAB? is it a different style locknut? are my studs pulling out? is there some unknown to me very high temp locktite? TIA Phil