tl4c gearbox problem plus other noise

hi there

i have a gearchange problem from first to second gear all the time from the first time almost i bought the car.now the problem its almost all the time i m gearing.scratch scratch scratch all the time.i changed gearoil at 5000km by my self in renault authorized dealer the phenomenon was reduced but until now(10500km) the problem exists and now is not so rare.the gearchanging is always done but with scratch.any advise mates???before i have to shout like an idiot to my authorized dealer.like a very good oil for example before i **** with them?
And second one prob,i m hearing a small bam when i am gearing again and also when there is small bumps on the road.i have to specify that i changed exhaust before 1 week.is there any possibility to be the exhaust(the 2 silencers)cause from there i think is is the bam.probably is not hanged up correctly or smtng?
i a waiting your suggestions cause i m so stressed about the gearbox and the noise also..
 
i have d-cat the car and the bam its like someone knocking you from the floor..i think the noise is coming from backbox place .thanx for your guess mate !
 
someone can provide me a very good gear oil?i search in web i couldt find for clio3 rs.for example quaife has only for auto transmission for clioIII.