I just bought a Hyper .21 8-port Race. I haven't run it yet, but i found another .21 with "boost". Not looking to buy ANOTHER motor but what is the "Boost" and what does it do? I've also been to Ofna's website and looked at the pics of both. Mine has a screw and a cap on under the carb where the tube of the boost engine goes. but mines not a "boost engine" its just a race engine and was wonder what its there for.