Our 3 briggs vangard engines all go through mufflers in 2-3 years each. I wonder do they make aftermarket ones that maybe last longer? First the inner baffle core of the muffler breaks loose and starts to rattle. Then the mesh fronts of the muffler rust through letting the loose insides come out...which straight pipes the mufler! 2 Have the baffles that have fallen out and 1 has a cracked header that everytime we weld the header it breaks directly next to the new weld. For taking off the exhaust headers to replace with new ones what is the best method? should I heat the bolts up before trying to break the nuts loose? 2 of these 18hp vangards are on Super Surfers.