Not sure what is different on a BEAMS engine to a non-BEAMS engine. It's not heard of over here. In Japan both 4 and 6 cylinder Altezza, GS300 and the V8 4.3 engines are labelled as BEAMS
However the Black top 3S-GE engine has some things not normally found to increase the performace:
dual vvt-i. Both intake and exhaust timing is adjusted
titanium valves
11.5 compression ratio (most engines are 10.5). The auto Altezza has 11.0 compression which is why it is 10bhp lower.