safeershah
Depends on your definition of "best". Most modified, yes. Definitely. Best? It depends...
HKS themselves use a 2UZ-FE Iron-block V8 out of the Land Cruiser, put in a forged crank (de-stroked), pistons and rods, and Turbocharge it to 1500 BHP. When they say; "No replacement for displacement", they aren't lying.
The beauty of the B16 is that it's a very good engine to do N/A tuning. The 2JZ-GTE can't spin as fast, but can hold a lot of boost.
The 4G63 Turbo can do both 
Although to be honest, we can discuss for weeks which engine is best and we won't find the definitive answer.
An Alfa engine isn't the most powerful, not by a long shot, but once you hear it revving into the 7s and 8s, you won't go back to anything else. it's not raw power that matters here (not that it's slow) but it's the raw energy that it emits.
