u dont hav to hav a intercooler, it would run better if it did cause there air going into the manifold would be colder,
waste gate isnt necessary, would make it sound cool tho,
and if its idleing rough, locate the idleing screw usually on the throttle body and open the throttle up a touch more, if still idles rough, do a good service on it, (plugs, leads, oil ect)