We have, in fact we replaced our turbo unit kasi sinabi kelangan na daw pero sa totoo lang pwede pa ayusin...

Pero we replaced it with a surplus unit for 50k sourced by A1 in Del Monte Ave. Later on we learned na hindi na pala sila matapat, pero the turbo unit they sourced for us sabi nila surplus unit daw pero it looked really new and we had no problems with it naman.
It may be true that the turbo is the problem, but check first with other mechanics to make sure that it really needs replacement. Some good places would include Malabon Diesel and Central Diesel. AFAIK, they have the equipment and the know how to fix Troopers and I believe they should be able to source parts for them, at a much cheaper cost than the casa.