An intake assembly (100) for an internal-combustion engine (2) comprises one intake duct (104) for each cylinder (CY), which communicates with an airbox (106) that comprises, inside it, a filtering element (114). Each intake duct (104) communicates with the airbox (106) by means of a respective throttle body (108). A monitoring channel (120) connects the intake ducts (104) together and is configured for perturbing in a negligible way the dynamics of the fluid inside the intake ducts (104). Associated to said monitoring duct are sensors for monitoring the pressure inside the monitoring duct and consequently designed to send signals indicating the value of pressure (P) of the fluid taken in by the engine to an electronic control unit.