What is the size of the stock intake hose? 2.5" or 3" or ?
(The hose that connects to the Air Box)

 

I believe its 3...

 

Will the larger size hose increase speed?

 

If you mean hp, probably not. It all has to do with volumetric flow efficiency. I won't bore you with the details but generally a hose thats too small or large will lose that "sweet spot". I say stick with the size thats there. Besides that hp gain woud be marginal at best. You're much better off doing doing a throttle body honing and boring.