The 1NZ is a workhorse reliable engine and you're taking on a big and potentially fatal project to add a turbocharger to it in Pakistan. It needs a decent budget, good planning, and the skills to tune your car to avoid killing the turbo, the engine, or both.
You'll need a lot of parts - an exhaust manifold, a source for an oil feed, an intercooler. You'll have to manage fueling, airflow, lambda, temperatures... It is not a simple task.
"millage" and "Hp we can gain" is the least of your practical concerns.
