New investigations reveal that the World War II-era plane that crashed at the Reno Air Race show Friday, killing nine people, had undergone a radical makeover to increase its speed at the cost of stability.

In the overhaul of the Galloping Ghost, the 65-year-old plane lost a full 10 feet off its wingspan. The ailerons, which control balance, were cut down from 60 to 32 inches.

The purpose of the makeover was to make the plane faster and easily maneuverable, pilot Jimmy Leeward said beforehand, but he was unsure of its effects. In a podcast uploaded on YouTube in June, he said, I know it'll do the speed, the systems aren't proven yet. We think they're going to be OK.

Leeward died in the crash.

Investigators are still trying to find out the reason behind the deadly crash. They are working on the elevator trim tab - a piece of the tail that helps the aircraft at the time of takeoff but was found broken before the crash at Reno.

The accident took place during the National Championship Air Races and Air Show in Reno, killing nine people and injuring dozens. According to the records, Leeward was the 20th pilot to die at the air races since its beginning, but Friday's crash was the first incident that took lives of the spectators.

Leeward, real estate developer from Ocala, Fla., was flying the World War II plane, a P-51 Mustang, according to a statement published by the show. The plane took a sudden upward pitch and then twirled a few hundred feet off the ground and plunged into the VIP box seats, witnesses of the tragic incident reported.

National Transportation Safety Board spokesman Terry Williams said his agency would do a thorough investigation of the modifications done in the plane. We're not saying they did something right or wrong in this accident. We look at all angles in every accident investigation we do, Williams said.

The event has been canceled and a memorial service was organized for the pilot Saturday afternoon.

Leeward was a well-known stuntman and air racing pilot who flew more than 120 races. He participated in air races in the 1970s and owned an air racing team.