Re: [MBZ] Partly OT - cold air into exhaust

[Mitch Haley]

I don't think it's cold air, but rather oxygen, that burns exhaust valves.
Open headers won't do it, but open ports with no header/manifold will. 
Like Alan said, carbon monoxide under the car isn't good, keep the fan
on high, with fresh air coming in from the cowl, so keep the cabin 
pressurized and hopefully exhaust infiltration will be minimized. 
Mitch.