If you notice the boost drop off at high rpm's, say a little before redline, that is normal. You will have a boost drop at that time due to the flow happening inside the turbo. Basically, what is happening, the turbo can't up with whats going out and whats going in. This happens with smaller turbines mostly. Larger turbos don't do this as much, but all do it to some extent. I won't go into a long dragged out discussion of what is happening...probably boring. As I said, if it is happening a little before redline, don't worry about it...unless it is dropping down to almost nothing. You also don't want it to spike either. If for some reason or somehow it raised (which is highly unlikely but something wrong with the wastegate lets say), that is very bad and you want to have that fixed.

 

What unit of measurement in pressure are you using there? I was assuming you are using the pascal units. .1 megapascal (MPa) is 14.5 psi which is a good stock boost level. I noticed that you have a 'k' in there. If you are reading it as kilopascals, then your boost is extremely low! .5kPa is only about .07psi. You probably wouldn't even feel that. Anyway, your problem could be a few things. If it is doing it at wide open throttle at that low of an rpm, it could be your wastegate. For some reason, it could be opening too soon and dropping your boost. If it isn't doing it at half throttle all the way to redline, it wouldn't be a hose leak because it would do it whether or not you are open or not. Could be some type of a vacuum leak from the intake to the wastegate. Maybe something wrong with the stock boost controller (ECU problem). It shouldn't be dropping at that low of an rpm. As I said before, at higher rpm, it will do that..a little. If your car is still under warranty, have them check it out.