So you've decided you want to turbo your 4.0 and naturally, this is one of the first things you think about. Up until recently your only option was to build a manifold. You could either build one from scratch or base it off of an existing header. Personally, I preferred to use Renix manifolds because they are a good single outlet log style manifold which gives you a lot of room to work with. The later manifolds are problematic because they are basically two 3-1 logs joined at a collector which is prone to cracking. Furthermore, the collector is angled back making it difficult to plumb the manifold forward, which is where most people prefer to locate the turbo. On my latest build, I decided to build a manifold from scratch in order to keep it tight to the head and have the turbo mounted right in the grill without the need to route the pipe under the manifold. A completely custom manifold is expensive and time consuming to make so I wouldn't recommend if its not required to reach your goals.