sentences:  Materazzi thus saw the advantages of the comprex system but also its difficulties and prepared also a second iteration with two smaller Comprex systems driven by hydraulic clutch instead of a belt but this was not used since the turbocharger was deemed simpler and worth pursuing.Hence Materazzi proceeded to perfect the following iterations of powertrain to obtain increased power and reliability.The 126CK was first tested during the Italian Grand Prix in .