The first thing we focus on, is the water temperatures, as our radiators have become somewhat famous in the Delica community you might understand why. Many people not used to the tuning of a small diesel engine and being misled by tuners of larger engines might have been fed advice that alarms them but not understand why, such as EGT's. The first step in bringing down your engine temperature, and all the temperatures associated with it is by bringing down your water temperature. With a low water temp you will see improvements across the board in other temps. We start this process with our aluminum radiator and lower temp actuating thermostat. Many old radiators are often in bad shape, half filled with debris, as well as just too small for the type of driving you want to be doing in your van. The lower temp thermostat, some of you might be wondering 'Why would I change what the factory put in there, the factory knows best!." Well that might be true 25+ years ago in a much colder climate than you are driving in. So we believe by our tested and proven results that changing the factory JDM (82c/88c in winter package) thermostat greatly helps in reducing the water temps along with the radiator. First off, old thermostats get slow and don't operate at their designed temps which is a problem in itself. Secondly, ours 71c thermostat allows the water to flow freely and quickly through the radiator which is often believed to not be good for cooling but that's a fallacy. So to sum it up our first improvement is simply changing these two items.