What are common reliability mods for JDM cars?

Common reliability upgrades include an aftermarket radiator or at minimum a flush and new thermostat (Japanese roads run at different temps than US highways), upgraded intercooler piping to replace aging OEM silicone, a cooling system pressure test to find leaks, a boost leak test, fresh boost hoses, and a wideband O2 sensor install for tuning. On turbocharged cars, an oil catch can prevents crankcase vapors from fouling the intake.