BMW pulled out of Formula One and the engines were badged Megatron through a deal with Arrows major sponsor USF&amp;G, but the British team had their best seasons yet, finishing seventh in 1987 and fifth in (the final year for turbocharged engines) thanks to frequent points finishes by drivers Eddie Cheever and Derek Warwick. While 1987 and 1988 were Arrows' best years in F1, they were also the cause of frustration for the team and its drivers Warwick and Cheever. At the start of 1987 the sports ruling body (FIA) mandated that all turbo powered cars were to use a pop-off valve in order to restrict turbo boost. This was done not only to slow the cars down for safety reasons, but it was an effort to curb the rapidly rising costs of Formula One. The problem for Arrows was that the valve would regularly cut in lower than the set limit (4.0 bar in 1987, 2.5 bar in 1988). This meant that the Megatron engines were not producing their full power. It took the team's engine designer Heini Mader until just before the 1988 Italian Grand Prix at Monza (Round 12) to find the solution, which was simply moving the valve closer to the engine, something Honda and Ferrari engineers had long before discovered. Although Cheever and Warwick finished the race in 3rd and 4th respectively, it was too little too late as the turbo era ended after the 1988 season.