Red Bull Racing is facing a 'significant' challenge to incorporate a 'double-decker' diffuser into its Adrian Newey-penned RB5, but team principal Christian Horner is optimistic of being able to introduce the new design in 'one of the early European races' - and with it take the fight to Brawn GP at the very front of the grid.

Red Bull has on balance been the quickest of the non-diffuser teams over the opening two grands prix of the 2009 Formula 1 World Championship campaign in Australia and Malaysia - and again in free practice ahead of the Chinese Grand Prix this weekend, when the Milton Keynes-based concern was the only outfit aside from Brawn, Toyota and Williams to feature up inside the top eight at the end of the opening day in Shanghai.

With the FIA Court of Appeal having definitively rejected a protest against the three teams in question, the onus has been placed on the remaining seven competitors to come up with their own innovative designs as they scrabble desperately to get back onto a level playing field with F1's new pace-setters - before it is too late.

Due to the particular design of its Renault-powered contender, Red Bull is likely to face a more sizeable task than most - but Horner is confident the team will get there.

"I think after the appeal hearing the situation is now closed in that the diffuser is obviously allowed," the Englishman acknowledged. "For us it has a significant impact, because we designed the car around how we believed the regulations should be interpreted and obviously came up with a very good car.

"The benefit that diffuser offers is significant, and obviously if you haven't incorporated it into the car design from inception it is something that is difficult just to bolt on, particularly in our case as an independent team. For us it almost represents a B-spec car, so it is a significant change to the rear end of the chassis in order to try and optimise it and integrate it into our design solutions.

"It impacts on the whole rear end of the car. It is significant, and obviously the only hole it has left us is in our budget. It is a significant amount of cost in not a great climate, but [given] the performance you can see today - [with] six of the cars in the top eight running that solution - we have to do it in order to maintain our competitiveness.

"It's going to be a real challenge to develop the cars through the season without testing - it really stretches the team - but simulation tools, whether they be wind tunnels or cfd, seem to be getting closer and closer in correlation to the track, which means that you can hit the circuit with a large percentage of items that you can bolt on and know you are going to get some performance out of.

"The guys, led by Adrian, have done a fantastic job this winter and the decision to release the car late was the right thing to optimise the time in the wind tunnel, but now to be faced with an upgrade with the quantum of this one is going to be a significant challenge. [It is] difficult to put an exact date on when we will be able to introduce our own solution, but it will be one of the early European races.

"On the positive side is looking at the performance of our car so far this year. Without it (the double-decker diffuser) we have been pretty competitive - the only car in the top eight today with if you like a standard solution - so hopefully what we can look forward to is a further step in competitiveness when we do introduce it."

Despite the governing body's final verdict on Wednesday, Horner remains adamant that Red Bull and its six non-diffuser allies were in the right with their designs, and that the three dissenters were 'certainly against the spirit of what was set out within the Overtaking Working Group' - even if he conceded that 'there was a lot of ambiguity within the regulations'.

"It's no coincidence that seven teams didn't go down the double-diffuser route," the 35-year-old underlined. "Obviously a lot of work was done in the Overtaking Working Group, and within the regulations there is a spirit or essence of what the regulations are set to achieve. Certainly the precedent of holes in the floor, from our perspective, was deemed to be illegal, so that's why we chose the route that we did to protest the cars together with our colleagues at the first opportunity.

"That wasn't after the cars had run; it was before they had run in Australia, to really get clarity. Obviously the stewards and the FIA made their position known there, and then the option to us was to appeal that. We feel that we had a fair appeal hearing, where the facts were presented from either side. I think the bottom line is that there was a lot of ambiguity within the regulations, and you can call it a clever interpretation, if you like, that the three teams have taken.

"I think it was certainly against the spirit of what was set out within the Overtaking Working Group. However, the court found that these diffusers are permitted. The teams obviously were in dispute with each other, but I think it's important that FOTA (the Formula One Teams' Association) sits down in the near future and discusses the issues. For sure it's our biggest test in its infancy, but I think it's important that these issues are discussed behind closed doors and solutions are found.

"As I say, we felt we had a fair hearing, we presented our case which was listened to carefully but now we're in a situation where, as they are permitted, we have no choice but to develop our own solution. That is obviously time and money and a big development channel that becomes open, because the underbody is the most powerful aerodynamic device on the car and so lap times will continue to tumble significantly as the solutions are developed."

Horner was also asked about KERS (Kinetic Energy Recovery Systems), which RBR has yet to employ in 2009 and which he described as 'more of a strategic tool than a performance tool', in that it can maybe gain a driver ten metres - or a row - away from the start-line, and as being of greater use for defending a place rather than for attacking.

Despite being happy with the technology's reliability from extensive winter testing, he contended that 'in terms of ultimate performance we don't feel it has earned its place on our car yet', adding that judging by Ferrari having ditched the device for China following repeated issues with it, 'other teams are coming to a similar conclusion to that of our own'.

On the subject of drivers, finally, it has been a bit of a tale of two halves for the energy drinks-backed outfit in 2009 to-date, with Sebastian Vettel having displayed the pace but Mark Webber having brought home the results. Despite likely podiums going begging in both Melbourne and Sepang, Horner is confident that he has the right men for the job - and that they will push each other and the team forward over the course of the campaign.

"Sebastian has obviously been part of the Red Bull family for some time now," the former racer acknowledged, "but he's been very, very impressive for somebody of such a young age. He's got a very mature head on his shoulders, [and is] obviously very quick. He was desperately unlucky in Melbourne; it was a racing accident.

"When he started with a penalty in Malaysia it was always going to be a difficult weekend for him, but he raced well. The conditions were obviously desperately bad, and he was unlucky to go off just before the race was stopped. He's only going to get better; he's still very young. He's pushing the team very hard and he's also getting the best out of Mark as well, who has come back after a hideous accident over the winter.

"Obviously in November he was wondering if he still had a grand prix future with a metal rod in his leg. He then got back to the UK in early January and forgot to mention that he'd also broken his shoulder. The recovery that he's made is testament to his determination and commitment, and the fact that he's back in the car so quickly and competitively is great from a team point-of-view.

"The guys get on very well and I think they will push each other all season-long - and from a team perspective that's great because we've got two guys that are really driving the wheels off the car. I think it's a really positive aspect for Red Bull."