So you've installed a high flow cold air intake and a four inch exhaust, but you're still not getting the spool up and lower EGT's you were hoping for.  Did you ever happen to look at what's between your intake and exhaust?  How about a restrictive intake manifold!  As you can see in the above picture, the restrictive factory intake manifold on the left has an angular design promoting turbulence and the smaller diameter creates a bottleneck effect for the airflow you're trying to rush through your Cummins.  All of the performance intake manifolds that we carry feature a larger plenum for increased airflow, and smooth radius turns to reduce turbulence and intake pressure losses. 

Most of our manifolds feature several ports making it easy to hook up a boost gauge or install a nozzle for nitrous, propane, or water methanol injection.  And besides the purely functional attributes of these manifolds, how about the pure intention for them to look good!  There is always something to be said for popping the hood of your Cummins and having a well dressed out engine compartment, as opposed to a dark, oil stained cavity that seeks attention.  So give us a call, and we can help you determine which manifold is best for you, and if you haven't already gotten a cold air intake or exhaust, we'll help you decide which setup is best for you and your truck.