CHARLOTTE - NASCAR's decision Wednesday to rein in Toyota's horsepower advantage in the Nationwide Series is likely to fuel the perception the manufacturer would spend its way to competitive dominance.

Toyota has been successful this season in all of NASCAR's top three series -- Sprint Cup, Nationwide and Trucks -- but nowhere has the dominance been more evident than in the Nationwide Series, where Camrys have won 14 of 21 races.

Joe Gibbs Racing, in particular, has enjoyed the most success with 13 wins coming from four different drivers, including nine from its No. 20 team.

As early as March, owners in the series including Jack Roush and Kevin Harvick, were raising the warning flag of a distinct horsepower advantage by Toyota engines in all three series and in particular Nationwide.

After another round of chassis dynometer tests -- which measure rear wheel horsepower -- at Chicagoland Speedway two weeks ago, NASCAR had seen enough.

The sanctioning body issued a technical bulletin Tuesday night requiring all engines with a cylinder bore spacing more than 4.470 inches to use tapered spacers with smaller holes.

Although the bulletin did not name Toyota specifically, Toyota's engine is the only one that fit the criteria. The change is effective beginning with Saturday's race at O'Reilly Raceway Park in Clermont, Ind.

Toyota officials did not take kindly to the news.

"We're extremely disappointed in NASCAR's decision. In our opinion, there is no technical justification to penalize the Toyota engine utilized in the Nationwide Series," said Lee White, president and general manger of Toyota Racing Development USA.

"The success of the Toyota Camry this year in the Nationwide Series is the result of hard work and achievement by all of our race teams."

Robin Pemberton, NASCAR's vice president of competition, said the sanctioning body has on numerous occasions taken steps to help "level the playing field among our competitors."

"Toyota started from the get-go with a new style engine while the other manufacturers are still in the process of producing theirs," he said. "I guess you can say they have excelled more than we anticipated."

Asked if Toyota had done anything wrong, Pemberton was adamant: "Toyota has done nothing wrong whatsoever. They absolutely were working out of the box we set for all teams."

Pemberton admitted it may appear Toyota is being singled out for their success, but maintained it was NASCAR's responsibility to ensure no manufacturer had a competitive advantage.

White warned of larger consequences to NASCAR's decision.

"Unfortunately, the decision by NASCAR could be more far-reaching than simply mandating Toyota to adjust its Nationwide engine," he said.

"The real impact will be felt by the Toyota teams as they adjust to the change, work to remain competitive for the remainder of this season and attempt to line up their sponsorships for next year."

Although it is true NASCAR has directed rule changes in the past toward individual manufacturers, it has been some time since it has done so during the season.

The most recent in-season rule change directed at a single manfuacturer was NASCAR's decision in April 2007 to disallow the use of one of Toyota's four intake manifolds for the Truck and Nationwide series. In recent years, most -- if not all -- rule changes have been made during the offseason.