Looking to make a comparison between a FMIC and stock location aftermarket IC the GTI was driven with each along a loop that allows for a good amount of control of the drive time along the route.
Recording was made of the turbocharger outlet temperature, intercooler outlet temperature, ambient air temperature, and vehicle speed. The temperature readings were sufficient to allow the calculation of intercooler efficiency throughout the drive.
The comparison of efficiency is shown on the chart:
Higher efficiency is more desirable.
The chart shows close similarity between the two intercoolers. Interestingly during the low speed portion of the drive, approximately time 1600 to 2000 the efficiency of the stock location IC is slightly higher than that of the FMIC.
The two instances of moderate acceleration, approximately time 900 and 1200, show similar efficiency being achieved by each intercooler.
A final unexpected result is seen during the idle period, around time 800-900. While stationary on the side of the road the FMIC efficiency drops slightly further, approximately 8-10%, than the stock location.