check your bolts on the turbo are all tight,because mongoose has no flexi in it, it rips the bolts out the turbo you wont hear it idling but will sound like a tractor when movin,put it under load when drivin and you should hear it loud when the revs pic up you cant hear it so much
done the same on mine only two options are gettin a flexi fitted or keep tightenin the bolts every couple of days.your choice