Are you talking about williams ? they have a dual exhaust system with headers that you bolt up rather than weld. They also have the heat plate that goes with the stock intake manifold, your get heated air from the headers directed to the plate which then keeps the manifold warm. They told me that their headers are built so that they use an o-ring gasket, for a better seal. The kit I'm looking at costs $600.00 for headers and dual exhaust. The pipes runs straight out the back under the bed vs. going out behind the drivers side rear wheel.
I'm also going to use stock manifold with the holly progressive 2 barrel vs. multi carb. Nothing fancy, just want alittle better performance with a kool sound.
Enjoy

1954 Chevy 3100 5-Window
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