The vertical flow configuration as specified by APS spreads the charge air flow evenly over a far greater number of internal passages and results in significantly less restriction. The path length of each internal passage is also shorter, further improving air flow over a horizontal design. The net effect is a short route with many passages resulting in a massive charge air reduction but with improved air flow.
Air flow is momentum based and the end tanks on the APS intercooler are designed so that an equal mass of air reaches each internal passage.

Importantly, the APS intercooler uses the latest in Bar and Plate core technology, not low cost off the shelf units. Other than the fact that the APS intercooler core boasts the highest flow and greatest temperature reduction, the bar and plate construction results in an inherently strong intercooler core of high thermal inertia. The advantage here for the performance street car and drag race enthusiast is that with the core's high thermal inertia, massive reserves of cooling capacity are available in situations where ambient air flow over the core is low. So, after a power run to heat tyres prior to staging for a quarter mile pass, there is plenty of intercooler capacity to launch with full power at your disposal.
The true dual entry design of the APS intercooler system allows for the ultimate in true equal length balanced ducting from each turbocharger to the intercooler. This ensures the optimum utilisation of the intercooler core by spreading the charge air from each turbocharger evenly across the entire intercooler core - This is efficiency at its best!

Intercooler ducting length is critical on the LS1 in order to achieve balanced induction and excellent driveability. By designing the turbocharger to intercooler ducting specifically to be of equal length, each turbocharger experiences the identical effective air path to the intercooler which results in totally balanced turbocharger performance (it's like having two separate intercooled turbo systems - one for each bank of cylinders). Other systems that are designed with unequal length, experience boost pressure and air movement issues where under certain conditions, one turbocharger pushes air back through the intercooler and into the other turbocharger ducting. As air movement is momentum based, this is simply wasted energy that should be better put towards producing higher horsepower, not restriction.
The advanced APS dual entry intercooler not only solves this problem but allows APS to utilize true equal length ducting - the most efficient intercooler system routing for the intercooled twin turbo LS1!
The APS intercooler core is of internally and externally finned construction and offers significantly enhanced flow and heat exchange performance, particularly at high charge air mass flow rates (High boost pressure and high engine power levels). Also, unlike other manufacturers of intercoolers who reduce cost by using low cost off the shelf tube and fin cores, the APS drag race specification bar and plate intercooler is designed with the optimum ratio of intercooler core surface area to intercooler volume - unlike inferior quality intercooler cores that are very shallow . The result is an intercooler system with outstanding flow and cooling performance, particularly at high engine power levels of up to 1,000 hp.