Exhaust, ride height top NASCAR's worry with COT (cont'd)

Hamlin said his personal trainer called the trainers of other Nextel Cup drivers and found that several of their clients had skipped scheduled Monday morning workout sessions because they weren't feeling well. Kenseth suffered a double blow, with a cracked exhaust pipe melting a basketball-sized hole in the absorbent foam of his No. 17 car.

"Half of our door foam was burned up, and we had a hole in the carbon fiber and I had to breathe that stuff all day," he said. "So that's definitely a big concern for me, especially this week and in the future as we get in the cars with right-side windows. That stuff burning, I don't care what they say, whenever you take something man-made like foam and all that stuff, when that stuff melts and burns, I know the fumes and smoke coming off that can't be good for you."

Kenseth said NASCAR officials told his team the foam was installed improperly, something the No. 17 crew refutes. Darby added that some teams neglected to add the false floor that supports the foam above the tailpipe area, causing the foam to melt when it was exposed to the additional heat of the broken exhaust system. Another issue was the thinner material some teams used to build their exhaust pipes.

"If you looked at the materials that were used to construct tailpipes on our old cars, they ranged probably from 83-thousandths [of an inch] in thickness to 120-thousandths in thickness if you really wanted a robust system," Darby said.

"The majority of the tailpipes that failed last week were constructed of either 49-thousandths or 65-thousandths, thin material. So I think that because the tailpipe configuration is smaller and weighs less, a lot of the teams felt like they could probably get by with a thinner overall material. In fact, when you apply the heat of the exhaust and everything, they did crack and they did fail."

Attempting to avoid a repeat of last week, Kenseth's crew planned to install an additional heat shield and further space out the exhaust pipes off the frame rail. Other drivers like Jimmie Johnson take the additional step of breathing pure oxygen before and after an event in an attempt to flush the carbon monoxide from their bodies. Johnson takes it for a hour Friday, an hour Saturday, an hour Sunday before the race and an hour afterward if he can.

"That's really when you feel it the most," Johnson said. "Going into an event, you're usually hydrated, you aren't feeling too bad, you have had a chance to recover. The biggest things really come after the race, if you can get on some oxygen. It helps you out a lot."