Christian Horner has warned Red Bull Racing's rivals that if they think they will vault ahead of the early-season F1 2010 pace-setters with the addition of the RBR-inspired exhaust-blown rear end, they had better think again - as he suggests they 'overestimate the benefits' of the aerodynamic appendage.

After the energy drinks-backed outfit stole a march on its title adversaries with the blown rear end - which diverts exhaust gases to improve airflow to the car's diffuser - other teams have been frantically playing a game of catch-up.

Ferrari, Mercedes Grand Prix and Renault all introduced their own versions of the innovation for the European Grand Prix in Valencia last time out - with the Scuderia boasting before the weekend of an improvement in lap time of some eight tenths of a second - but in truth, none of the three showed any mark?d progress.

McLaren-Mercedes is similarly poised to debut its interpretation of the concept in this weekend's upcoming British Grand Prix at Silverstone - in addition to new cooling, suspension and dampers for the MP4-25, it is believed - but Red Bull team principal Horner has cautioned against raising expectations too high.

"Our rivals overestimate the benefits of the blown diffuser," the Englishman told German publication Auto Motor und Sport. "It's only about two or three tenths."

Those sentiments are corroborated by Sebastian Vettel, who explained that the exhaust-blown rear end is just one part of a greater package on the Adrian Newey-designed RB6 that also makes use of a unique pull-rod suspension layout.

"It gives us a bit, but only together with the whole package, and that includes our rear suspension," the young German reasoned. "That can't be copied during the season [due to chassis homologation rules]."