The engine control unit (ECU) is located inside the airbox on early bikes. On newer models, it's behind the head. Neither is a good location. Inside the airbox, it impedes access to the air filter and makes removal difficult. Behind the head, it is exposed to weather and engine heat. But there's not much unallocated space on a trials bike and compromises must be made.
The left-side photo below shows the “integrated” nature of the ECU. The 3 large cylinders adjacent to the connector are filter capacitors, probably for the DC-to-DC converter and the fuel pump voltage regulator. The blue rectangle is the CDI's energy-storage capacitor. There are 2 inductors adjacent to the blue capacitor, which I assume are for the CDI's DC-to-DC converter.
In the right-side photo below, the TR280i ECU is the smaller of the two. The larger one is for an Arctic Cat snowmobile.
Apologies for the small photos, they were captured from the Kokusan Denki website.