you need to make sure the motor makes it to normal operating temps. at the very least.

 

I'm not sure about the pollution avoidance aspect, but the vacuum
does reduce air resistance of the pistons and connecting rods
at high rpms, resulting in more power. There are special
pumps in the block to create this vacuum, which isn't standard
in most "normal" engines.

If the turbo seal provides less vacuum, this may be why there is
slightly less power with that seal.