Honestly my speedo does not work - judging by the digital speed sign, it was a true 45 - the engine seems to be in good order and i would think that 55 shoudlnt be a problem - i went from a 2002 ford explorer to this so maybe i think it sounds louder and revier than it really is - the fact that there is slop in the steering wheel doesnt calm my nerves either even at 45 - thank you for the responses - first and second pull really well and sound great, its just on the highway that i begin to question things - no interior or sound proofing may be a culprit as well.