If you plan on running low boost, I would go with an external gate. Internals seem to have some issues in the lower boost range. IF you are running 20+ psi daily, you should be able to get away with an internal gate. On a personal note, I hate internal gates for any boost level.

If I were you, I would seriously consider the FP3052 setup. It's all the turbo you will ever need and outflows any other mitsu housing on the market. It is costly, but very much well worth it. It's very pump gas friendly and very easy to tune with DSMlink. With the DNP, FP3052 and o2 hosuing I was making full boost at 3400 RPMS. FPGreen and 3052 are prolly the two best street turbos around. By street turbo I mean quick spool with good power and friendly with pump gas (91-93 Octane).