Problem Or Not (Turbo Pipes)

Recently bought a mk3 mondy 2.2 tdci. Not having a turbo before, I'm none the wiser to potential problems yet ?? But the engine/turbo makes a "weezing" sound noise wen changing gears. I actually thort it was just turbo noise herd from inside the car, but a m8 driving behind me on the way into work asked me wot the noise was as he herd it in a car behind me. So I guessing the noise is just as loud outside the car ?? The only problem at the min I'm aware of with the intake and exhaust, is the the flexi pipe is not attached to the exhaust pipe at the front end at all, so back box is not even in the equation at min. Would this have any influence on previous air pressures within the system or cud it be a split pipe sum where ?? From wot ive read split pipes and exhaust issues Can cause noises. I'm changing the flexi pipe at the weekend anyway but Wud be handy if I shud be looking out for pipes aswell ??