It was no surprise that some of the teams had already been spending time and money on developing double diffusers before their legality was confirmed — especially ones that looked to be struggling - and it was more of a surprise that others, particularly Ferrari, had not created something to fit on to the car in time to at least test in Shanghai.
But then, it is not as easy as that.
Any aerodynamic modification needs to be developed as part of the whole package. A new diffuser, even though it is attached at the rear end, will affect how the air flows over the car right from the front wing, so there is much, much more to developing these double diffusers to fit into the aerodynamics of the single diffuser cars.
Also, integrating a double diffuser, because of the involvement of the crash structure, generally requires a not insignificant re-design to the rear of the car.
In Red Bull's case, their pushrod suspension makes it extra challenging and it will take them at least until Monaco to develop — and despite the team's pace on the way to victory in China, designer Adrian Newey has admitted it is worth doing.
But the two teams that did manage to get something in place in time for China, albeit an interim design, were Renault - perhaps because they had gone through initial stages of a similar design that was declared illegal by the FIA during the winter - and McLaren, who have been chasing every performance gain they can get.
McLarens had their new design on from the start on Friday while only Fernando Alonso got to use the new Renault double-decker, which was fitted on the Saturday.
McLaren brought in a significant development to their front wing, as well as to the diffuser, and Hamilton said the car "instantly felt better" in Friday practice. He finished fastest in the first session, probably on low fuel to make a point, and by the end of third practice the McLarens had posted five top-10 times out of a possible six.
By comparison, in Australia the team only secured one top-10 practice spot and in Malaysia only two.
But it is only in Q2 that the most accurate analysis of relative performance can be made, as it is the only session in which all cars are fuelled as low as possible to get the fastest time they can.
In China Q2, the two McLarens were running with interim diffusers while Alonso was the only Renault with the new parts.
Looking at McLaren's Q2 performance this season, their fastest car was 0.943 seconds off the lead pace in Australia and 1.121 secs off in Malaysia.
In China, with the new aero package, the fastest McLaren was 0.610 secs off the fastest car's pace — a gain, as predicted, of between around three to five tenths.
But in China the fastest Q2 lap was done, for the first time this season, by a single diffuser car, the Red Bull. Compared to the fastest of the 'diffuser gang', the McLaren was even closer, only 0.237 secs slower.
It's a similar, but less dramatic, story with Alonso,who did not have such significant aerodynamic modifications on the rest of his car. He was 0.822 secs slower than the fastest car in Australia and 0.922 secs off the lead pace in Malaysia.
In China, with the new rear diffuser, he was 0.673 secs off the pace of the fastest car — a gain of around 1.5 to 2.5 seconds. And he was 0.300 secs off the fastest 'diffuser gang' car.
It would be interesting to compare Alonso's Q2 time to that of his team-mate Nelson Piquet, who was running without the new diffuser — but Piquet has never yet made it into Q2, so it is a comparison that is unfortunately not possible! Shame.
These, of course, are interim designs and there are more steps to come. But it just shows that every little helps, and if the single diffuser teams were guilty of missing a trick in the regulations in the first place, the ones that did not get to work on a solution to put in place for China, as soon as the appeal was thrown out, dropped the ball a second time.
DATE PUBLISHED ON: 23 APRIL 2009