[SaabJohan]

To increase the power by 30% you usually only needs about .3 bar of boost, that's very low.

Using about .5 bar you will get almost 400 hp.

A good turbocharger in this class, using a twin setup could be a MHI TD04HL-15T-5 or similar. In a twin setup they will have a capacity for 500-550 hp, while also offer a fast spool up and a low boost threshold.

The turbochargers should be used with an intercooler, suitable ones can be found on small trucks.

Exhaust manifolds and downpipes must be manufactured, preferbly in stainless steel, at meast the manifold. It's recommended that you change the whole exhaust system.

Pressurised oil must be taken from the engine, and a oil return with a large diameter must be made which returns the oil back to the sump over the oil line.

Coolant to the turbocharger should be taken from a low pressurised place to the turbocharger and from the turbocharger to a high place like the water outlet in the cylinder head.

The most difficult part is probably o solve the fuel. This also depends on the fuel system and engine management how to solve it.