It's a common thing in South East Asia due to the fact that the mini throttle bodys are common (larger capacity scooters run 38mm tb's), and they like to run hack jobs of mods lol.
To do so in Aus, expect a gain of about 5kw at the engine, with a fair bit of custom fab work, not including tuning (which is a pain in the *Richard*) for about $4k. A turbo setup of $4k would net around 50kw.