Okay, since it seems that it's not even clear to everyone what we're talking about: Best summary of the RB Valencia upgrade package I've read so far: http://somersf1.blogspot.co.uk/2012/06/red-bull-valencia-gp-technical-analysis.html In a nutshell: RB increased the intake size of their tunnel under their sidepods because the old one wasn't getting enough air through it. Now, that air is funneled through the motor starter hole which increases the power of the diffuser and creates rear downforce. In my opinion, there is nothing wrong with that. Afaik this isn't new. Mercedes already asked the FIA to investigate at Australia and they said nothing was wrong with it. Additionally, I doubt that it would even be worth it to do off-throttle blowing because of how far the exhausts are from the diffuser now. Off-throttle blowing costs A LOT of fuel so I don't think RB would have such excellent race pace if they were carrying far more fuel than everyone else. Plus, the FIA can assess fuel levels even during races so they'd know if RB would be using more than everyone else. And on top of all that, in my opinion it doesn't sound 100% like last year. That characteristic 'crackle' when the driver lifts of isn't there anymore (or at least not to the same extent). Edit: Okay, I've probably not expressed that very clearly. There are some crackles, but I think this is just how the engine generally sounds and the louder 'pops' are simply from shifting down. I guess it's possible though that there is some small amount of overrun which is necessary to keep the engine healthy (Renault elaborated on this at last year's British GP) and doesn't give a significant performance boost, so the FIA wouldn't mind it. <- Last part is pure speculation though. Edit: And the Ferrari produces a similar noise.