I'm planning to run the factory 2" merge pipes from the Jeep, which are also the same as what the Dakota had. The only thing I'm intending to fabricate is the actual down pipes from the Magnum manifold exits to the primary tubes, and use all of the Jeeps' OE plumbing after that - might even retain the Jeep exhaust 'loop' pipe (just downstream of the cat) to keep the distances equal.