Dad (finally) gave me leave to build stacks if I want... It's not my main priority, but I want to spend some time thinking about it. (I have a lot of floor repairs before I can start) All I know about stacks is that I have a welder, and am not going to pay for a kit. I want to try the box splitter instead of the "y" piece. But I don't know if I want to go with dual 5", dual 6" or a single 8". This has to be PA legal, so I don't know about a muffler or if I even need one... I have a bone stock 7.3 idi. I don't know what I am doing, and need some advice. The truck is going to be a flatbed (Took the bed off today!) and I am going to build the stack or stacks in front of the bed. because of that I think duals would look better. Is it possible to find about 8" lengths of 5 or 6 inch exhaust pipe? I read something about a bigger downtube... I am not even 100% sure what that is. If I keep it stock, (which is 2.5 inch correct?) it won't sound as good + a bigger one should give it more flow and better performance right? But, I would have to run new exhaust all the way from the engine to the bed. The question is how big should I go?

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Could I run one exhaust tube straight off each manifold, into something like this, Google Image Result for http://www.dieseltruckresource.com/pics/data/500/Picture_0105.jpg
(that would count as a muffler if I'm right) and then have stacks? The exhaust would have 2x the flow right?

 

Dealing with the PA Legality, you'll have to check your county. In Allegheny Diesel's are exempt for the time being but I believe it goes on a county by county basis.

 

Are you gonna run heatshields?

 

Heat shields where? Not in the bed, I am going to have about a 6 inch gap between the bed and the cab so that I can put my stacks in. And I don't know if it even has heat-shields on the stock exhaust... Does it?