Re: engine spacer question
The main purpose is to minimize the transfer of engine heat to the intake. This would give you a cooler intake air temp thus more power.
On the downside if you inadvertently fold a gasket over or don't get a good seal you may suffer from "the more parts I buy the slower I go" syndrome!
There may also be clearance issues depending on other add-ons.
One of these days I will look into making my own.