no its just an old 50cc moped lol. sorry but even if it is running the best it could you will either be peddleing up hills or burning out your clutch.
but i guess a question to help you get an answer is
if you are going top speed and start up a not so steep hill will it bog down?
if you are at top speed and start going up a hill and it bogs down then you have a problem. brand new you could not start out on a hill and go up it.
if you weight is over 100 lbs then dont expect to climb any mountains. even if it had 3x the engine it does it wouldnt be pulling any grown men up a big hill.
id say get something over 100ccs but even then it wouldnt do much better. if you live in a hilly place and this is an issue id sugest something with a transmision thats made to do hills not something with a cyntrifical clutch.
goodluck and yes the drilled hole min your mufler could be helping or hurting. the best running moped i own has a sawed off muffler and is loud as shit. so loud it can only be riden in the woods but it proforms 2x to the same one with the same muffler but intact. so unless the hole is makeing wierd backpresure it should be ok.
if when you hit the gas it sounds good like well idk if it souds like its going from idle to topspeed smoothly then the hole should be fine.