My truck only has rattle can spray in boxliner on the floorboards, no window felts along bottom, half the weatherstipping is missing on drivers door and the straight piped exhaust dumps 8" behind the cab. I can barely even hear myself think doing 55.
There are plenty of good sound deadening products and the pricier ones are not always better. Use matting on floors and all accesible panels(including doors) and use a spray on deadener in spots you cant really reach with matting( inside door edges, B- pillar, under dash, etc) It will significantly quiet your ride...inside at least.