[Kenth]

Heat from the crossover is one factor of three that helps vaporize and atomize the liquid fuel to a combustible gas.
The other two is velocity thru the venturi and the amounts of fuel added.

If you reduce or eliminate one of these factors you will have to increase the other two to the corresponding degree.

This matters little or nothing at all for the race crowd, they starts at 4000 rpms and drives only a quarter of a mile at the time and could care less for drivability or fuel economy.

For anybody that has some insight in the principles of the combustion engine, how it works and why, knows the intake gasket steels are kids stuff and the molten aluminium fill in the siames channels in the heads are "racers only" when tuning headers for max performance beyond 5000 rpms.

FWIW