Re: twin phaser
Twin phaser relates to the variable valve timing of both camshafts independently, changing the timing of when the valves open and close. JTS relates to fuel injection directly into the combustion chamber at engine speeds of below 1500rpm - like VW group FSI and Mitsubishi GDI. The difference being that both these manufacturers use the direct injection below 3000rpm, Alfa from below 1500. This allows the (bigger) injectors located in the inlet manifold (as in 'normal' injected cars to cut in earlier and pump more fuel into the engine at a lower engine speed offering that power you talk about low down. Should also be more environmentally friendly at idle and economical below 1500rpm.
Linked to this is the sky high compression ratio which helps make the most of the fuel that goes in, but also necessitates use of complex anti knock sensor systems, the variable valve timing and of course the variable inlet geometry.