For the following reasons, the increased torque thing is an internet myth as far as I'm aware.
1. Mechanics with decades of experiencs have told me that they're only to reduce noise.
2. Alfa never put them on any model before the Euro noise regulations came in.
3. Autodelta and others make intake pipes for the GTV and GTA which completely do away with these chambers, with no documented loss of torque.
4. I've never seen them on any high-performance vehicle, which I would expect if they did indeed give more torque.
If the piping you're replacing them with is as big as or bigger diameter than the standard, you won't lose any torque by ditching the chambers.