well when I got my 99rs I was raceing nt eclipes and still beating them bye a car and after I made one i ran my intake pipe down the hole next to the air box to the front left side hole and put my arospeed filter their so like a cold/ram air intake and I still used my factory pipe just took the box off and when from thier alot of peeps say to take off the factory part and go pipe all the way but I don't think its going to stop air flow that much . I seen a dif more at high rpms like 4000 and up then low but then again when you race more then half the time you all ready moveing so I guess that would help right ? thy did a test on a honda once of dif intakes you should get about 5hp or soo other then the way i got it I think short would be better cuz the air gets their faster .. unlike mine is more forced into it the faster I got