Swirl flap changing is a job that would cost u less than 6,000 LKR. I got it done. And just to avoid the turbo going bust make sure u use the voltex breather valve on the car, which is was released by BMW to avoid the traditional valve getting clogged. It would cost u a max of 14,000 LKR. For 20,000 LKR u can sort these issues. I use one now, and it runs like a baby, but it was one heck of a specimen i found. And withonly 400km a month, i really feel im under utilizing a 320d's benefits. But its powerful, the low down torque is amazing.
Beware of older cars that have been facelifted. Both the diesel and petrol variants of these facelifts are huge improvements from the previous cars.