We have designed our intake manifold casting to enhance the performance of any Twin Cam or Big Twin.  Performance is especially enhanced when our cylinder heads are used concurrently.  These manifolds are very small in cross-section, tappered over the length of the runner, highly separated front to back, and straight as possible for the longest distance.  Even with the added length and sharp corners, our intake manifolds provide no restriction in the flow bench.  Of course who cares what the flow bench indicates, it is the dyno and the street that shows they really work. 

We have manifolds for any carburetor set-up. Stock Sportster manifolds are pretty good and just  need a little modification.