Eliminating exhaust system and header leakage means using good old fashioned street smarts.

Ask just about anyone who has run headers on a classic Mustang about leakage and there's nearly always a disappointing story.  Lets face it - only in recent years has header quality gone skyward - it's better than ever because competition for your business has never been higher.  The other half of the equation is proper installation.  That means it is up to you to ensure there's no leakage by installing the darned things correctly to begin with.

Rule 1 - always buy the best header gasket available.  Do not do it on the cheap.  It is easier to spend more in the first place than it is to have to replace gaskets again and again.

Rule 2 - all header flange and cylinder head contact surfaces must be hospital clean.  Any debris creates hot spots and immediate gasket deterioration.

Rule 3 - torque header to head bolts uniformly and with a torque wrench.  Yes, with a torque wrench.  Once those bolts are tight, check torque again.

Rule 4 - headers must not touch any part of the body or you will have unwanted noise.  If they touch - they don't fit your application even if they're the header the manufacturer calls for.  Too much time is wasted on headers that do not fit.  If they don't fit, send them back.

Rule 5 - use only the best locking header fasteners available.  Likely the best fastener out there is the Stage 8 locking header fasteners available at most speed shops including Summit Racing Equipment.  Stage 8 fasteners are fool proof because they cannot work loose.

Rule 6 - if your headers have a ceramic coating, take extra care not to damage the coating.  If it is damaged, you will have rust.  Heat will also escape.

When you install an exhaust system, make sure there's plenty of pipe and muffler clearance.  You want at least one-inch of clearance.  Have all pipe joints welded to completely eliminate leakage.  Overtightening clamps does not stop leaks.