Slamming the car i think makes the handleing worse, you turn in fast the rear would let go quicker because there is no roll! (i think) As for the gearbox give it a few days it will get better, mine seems to anyway! after long motorway journeys from lurgan to belfast this happens to me, i no its the clutch release bearing in my car! once it heats up it whines and makes odd noises! i have a gearbox if you need one am in lurgan? Dont know condition its got half drive shafts hanging out of it as it was cut from previous car, its got nothing with it!