[DKJones96]

would it do anything for a stock engine? and what is it?

 

[sloopercat]

Not much, if that is all you do. But, if you punch some holes in the air box, open up the exhaust, it does make a difference.

You basically reduce the spring tension on the AFM flap so that it goes richer quicker. Improves throttle response, but not ultimate HP.