'Pop-off' dispute ended, says CART

CART's statement said the modification that caused so much strife will return for good at this weekend's Michigan 500 and will remain for the rest of the season. The mod, which consists of a three-quarter-inch spacer at the base of the valve, was brought in as an attempt to stop manufacturers over-riding the existing maximum turbocharger boost pressure.

It was also confirmed that the maximum allowable boost will be restricted to 36 inches at Michigan and California Speedways - the two fastest tracks on the schedule - and 37 inches elsewhere.

The announcement came after four weeks of acrimony in which Toyota accused rivals Honda and Ford-Cosworth of cheating, while at the same time being on the receiving end of criticism for its active role in bringing the matter to CART's attention in the first place.

CART chairman and CEO Joe Heitzler said: "I am extremely pleased with the determination of all the parties involved to come up with a solution that preserves the innovative and competitive nature of our sport while maintaining a due process by which all members of CART may receive proper consideration.

"All of the manufacturers have expressed some frustration with CART's handling of this matter," he said. "We greatly regret the difficult nature of this situation and the difficulties that it has presented all of our partners.

"It is CART's position that it is our duty as a sanctioning body to provide strong leadership to our members, under the rule book, while maintaining a process enabling them to make informed decisions. Our conversations over the past three weeks have strengthened our determination in both these regards."

No official reaction has yet been received from the series' engine manufacturers.