So, on the yellow truck (79 F-350 460 C6), I just rebuilt the top end with a Performer manifold and a Holley 4160 600 cfm vacuum secondaries. I think the cam is stock.

Currently, I don't tow anything, but may tow my ski boat and will probably get a small house trailer for weekends at the lake.

The dual exhaust (factory?) meets at the muffler for a single exit. On my old 79 F250 460 C6, I had glasspacks and true duals behind headers. I've done a lot of reading about manifolds being better for low rpm's, and headers only being effective at higher rpm's. I've also read how only Hedman headers fit my truck. I don't want fenderwell exits.

So, the question remains - headers or manifolds?

ps - I'm in rural Arizona - so screw the smog stuff!

 

Headers... they'll increase HP and torque across the board.. Stay mild with sizing on true duals - at least 2.25-inch but not more than 2.5-inch tubing to maintain low end torque.

I recommend Stage 8 locking fasteners.

 

Thanks - I had not considered tube size. I do remember a lot of exhaust leaks - I solved that by RTVing two gaskets together on each side. And now that I think more about it - I went through an awful lot of starters...