Quote from espnf1.com; Grace period for blown exhaust limit ESPNF1 Staff May 18, 2011 The FIA has given the teams a grace period before enforcing a ban on the way exhaust gases are blown through diffusers. Formula One's governing body has concluded that the engine had become an aerodynamic aid controlled by the driver, which is not permitted in the regulations. In order to prevent this, the FIA will ban the blowing of exhaust gases beyond 10 per cent of full throttle, and had originally planned to impose the ban ahead of the Spanish Grand Prix this weekend. According to Auto Motor und Sport, however, the ban will now be imposed at a later date agreed with the teams to ensure that some are not unfairly penalised. Mercedes team principal Ross Brawn says the ban will have a significant effect. "These sort of staccato exhausts that you hear, I don't think you will be hearing anymore," Brawn told Reuters. Red Bull is widely believed to have mastered the blowing of exhaust gases through its diffuser, and the ban could be a result of a complaint from rival teams unhappy with the way it controls its engine. McLaren's Phil Prew had previously said that he believed Red Bull's qualifying pace to be down to the way it uses its engine to maximise the potential of the exhaust gases. "The use of elaborate engine modes may be [a reason it is quicker in qualifying], with the generation of downforce being quite highly influenced with the exhaust flows," Prew said. When asked if the ban was likely to be the result of a complaint, Red Bull team principal Christian Horner said:"It is inevitable and the unfortunate consequence of success."