The last kind of serious problem I had was with the solenoid valve (?)assembly. It affects how the boost pressure is regulated. Since I still have the stock twin turbos, I was told it was bound to happen. People with earlier versions used to change the actual hose within the unit themselves or had some shop do it for them. The problem was that it's really hard to open it up, change the whatever little thing and then to reseal it without needing to worry about any 'gap.' Since then, one would have to buy the whole assembly and reconnect those, which isn't as hard as that mentioned earlier. This is a problem that seems to happen after about 4 or 5 years.
The symptoms are similar to that experienced when you're running out of gas. As you're stepping, you feel like you hit an air pocket and temporarily lose acceleration. If you were in fact low on gas, it shouldn't recur after filling up. This can be avoided as long as you try not to apply pressure to make the turbines do their rightful job. It's uncomfortable though.
Another thing that is not a big deal, but shouldn't be overlooked, are the clamps on the hose (aftermarket parts are usually metal) between the turbine and the intercooler. Upon casual inspection, it seems fine but when I was stepping on it, I was able to hear something like a burst or gush of air from underneath. This can be a problem since the system won't be picking up correct data to manage the boost, for example. At high-boosts, who knows what would happen.
Anyway, there's gonna be some oil from the turbine that would make the inside of the hose slippery. Enough to 'pop off' or to let air ooze out from under the clamps when pressure is applied. Since the hose and rubber segments were fine, they were just washed to remove the grease from the inside so that the clamps would fit tightly. The outside surface of the intercooler to which it would be attached was also wiped clean.