I can confirm without a doubt
, that heat soak is not a problem with the CSL. It gets a ton of fresh air from the lower intake duct. Once you get on it, a flap on the end of the CF intake opens up to add more air and provides that intake roar.
I think one problem with running an entirely closed system is making sure that you get enough volume of air to the motor at high RPM. The longer the ducting, the harder this is to accomplish.