I have installed that unit on my 2.5V6. I did the following mods:
Z-engineering supercharger kit, front strut brace, lower brace, Novitec anti-roll bar, KW coilover, carbon fibre bonnet (19lb ligther than original), moving battery to the boot (saves 40lb from the front), 17" alloy, Bridgestone S-03 215/45-17 tyres, Zender body kit, Novitec pedal, doorpin and handbrake, Autodelta mid-pipe and exhaust.
The car doesn't feel much different in daily driving and in fact the low rev torque is a bit compromised as some engine power is drained to power the supercharger, but after 4,000rpm, it's a rooooocket! While I don't have chance yet to test the top speed, my friend who got the same kit tried over 260km/h on the highway.
What I plan to add are : Quaife or Kaaz LSD, GTA 17" wheel, rear strut brace, Japanese equal-lenght front pipe, ERL water injection,etc.....
There are lots of good tuning parts in Japan coz they love Alfa like crazy.
you can check out these sites: