In terms of boost leak, turbo outlet pipe as mentioned, "d seal" on the tmic (rubber gasket that connects onto the inlet mani) and perhaps the inlet mani itself is not tight upon the head etc. There's a few possibilities really...
PH1 306 XUD - 11mm VE, Big 'bine, TMIC = Plenty of coal, abuse, heatsoak and a power band of 4.3k - 6k = One shagged car.