NASCAR has addressed the heat issues that plagued last month's racing at Indianapolis Motor Speedway with a rules mandate for this weekend at Michigan International Speedway.

Drivers complained it was too hot in the cockpit of their cars with the high-drag rules package, which was first used at Indianapolis and will return at Michigan. The package reduces airflow under the car, so heat is trapped in the cockpit and several drivers were almost ill following the Xfinity Series race at Indy.

But NASCAR on Wednesday mandated a dual outlet duct be used on the right-side window to help ventilate the cockpit.

A day before the mandate, Brad Keselowski warned Sunday's race at Michigan would be "the toughest race probably of the year physically."

"The heat's going to be even worse this weekend," he said Tuesday. "There is a large amount of concern across both the teams and the driver for this rules package coming up to Michigan. Even though the track is wider and bigger, the significance of the draft is going to be even more important, so you're going to have to stay in line as much as possible. As you stay in line, the car gets less and less air because that's essentially how the draft works."

With the heat issue now addressed, the focus shifts to durability concerns at Michigan, the fastest track in NASCAR.

Keselowski warned that the high-drag package will cause parts to overheat, particularly in the drivetrain. Cars top 200 mph at Michigan in qualifying, and temperatures are expected to be in the mid-80s on Sunday.

"I would not be surprised to see a lot of car failures this weekend specific to heat relation as it pertains to the aero package and its kind of cause and effects. And inside the car I would not be surprised to see a lot of hot and worn out drivers after the race. We all know we're in for a handful of a race."

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SOUND GARAGE: Chip Ganassi Racing's drive to attract millennials will once again include an invitation-only concert at its North Carolina race shop.

Big Machine Label Group's recording artist A Thousand Horses will play Oct. 5 at the "Ganassi Sound Garage" in a concert that will be hosted by NASCAR drivers Kyle Larson, Dylan Kwasniewski and Brennan Poole, as well as IndyCar driver Sage Karam.

Last year's inaugural social media concert featured Cassadee Pope and won an industry award for NASCAR's "Most Creative Use of Social/Digital Media." The event will again be streamed lived.

The inaugural Sound Garage was for 200 social media savvy millennials and influencers, but Ganassi expects to triple that number this year. This year's event will also include sponsor participation from Target, McDonald's, Clorox, Kimberly Clark, Unilever, Energizer, Coke, Chevrolet and DC Solar.

Opportunities to attend will be given away by the drivers and A Thousand Horses via social media.

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JR MOTORSPORTS-BOWMAN: Alex Bowman will make his Truck Series debut this Saturday driving for JR Motorsports at Michigan.

JRM's No. 00 Chevrolet has primarily been driven by Cole Custer, but other drivers have filled in. Bowman ran two Xfinity Series races last year for JRM.

"The experiences I had racing for JR Motorsports last year were a lot of fun," said Bowman. "It'll be a learning experience for me being my first time in a truck. Watching the No. 00 team so far this season, I know it's going to be a fast truck and we'll have a shot to run up front.

"The main goal is to help these guys continue learning and improving on their overall program, particularly at the big tracks, so we'll try to do that and see if we can pick up a win at the same time."

JRM has picked up Truck Series wins this year at Gateway with Custer and at Charlotte with Kasey Kahne. Custer will be back in the truck next week at Bristol.

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KHI-MOTOCROSS: KHI Management, an athlete representation and sports-marketing agency owned by NASCAR champion Kevin Harvick, has signed 10-year-old Ryder DiFrancesco, who is considered the best amateur motocross rider in his age division.

DiFrancesco hails from Bakersfield, California, the same hometown as Harvick.

He's been competing since 2008 and currently rides a KX 65 for Kawasaki Team Green. He's also a member of Team Dunlop Elite, one of the preeminent amateur motocross sponsorship programs in the United States.

His multiple 2015 amateur national championships include a title at the prestigious AMA Amateur National Motocross Championship at Loretta Lynn's Ranch, two national titles at the GNC International Motocross Final, two championships at the Monster Energy Mammoth Motocross National, two at the California Classic Championship and a pair at the James Stewart Freestone Spring National Championship.

"Very few athletes win nearly every time they hit the track, court or field, but Ryder is one of those rare competitors," Harvick said. "He has done more in 10 years than most riders do in an entire career."

DiFrancesco joins a roster of KHI Management athletes and celebrities that includes: Miesha Tate, Ultimate Fighting Championship (UFC)'s top-ranked female bantamweight fighter; Rose Namajunas, UFC's No.3-ranked female strawweight fighter; Donald "Cowboy" Cerrone, UFC's No.2-ranked men's lightweight fighter; former NASCAR driver and current NASCAR on NBC analyst Jeff Burton; PGA golfer Jason Gore; and country music artists Jake Owen and Matt Stillwell.