Flowmaster muffler overheating

If you don't have vacuum advance on the distributor, adding it might help too

 

I do have vac advance, new unit last year.

 

There are many issues that could cause the hot exhaust/muffler some already stated others could be; too rich of a fuel mixture(yes rich, excess fuel burning in the exhaust especially if muffler is close to engine can cause an extremely hot muffler), to restrictive of tail pipes after the muffler, a small leak at the inlet side of the muffler(usually will be worse for heat in exhaust in a rich fuel mixture condition) are also some others to be considered.

 

The collective HAMB Tuning and Diagnostic Genius' have spoken, far be it for you and I to question why

 

Have you got the whistle tips on the flowmasters? They go Wooo.......

 

Mufflers are under p***enger footwells, thats as far back as they'll go.