Google is good, results for - "how to tell if a turbo is high flowed" in GOOGLE
taken from first results:
Australian Members..what does a "High Flowed" turbo mean???? - Mazda MX6 Forums: MX6 Forum
Hiflowing Turbos:
"Turbo sizes need to be properly calculated to get optimum performance and drivability for a given engine. Generally a hi-flow turbo will use the existing exhaust turbine from a factory turbo, with either a larger compressor wheel in the existing housing, or a whole new compressor assembly grafted on. It is generally the case that the existing turbines on factory turbochargers can support a larger compressor, so this is convenient way to improve the flow capability of your turbocharger while still keeping the original manifolding, oil feeds and etc. This process is relatively cheaper than going for a new turbo and associated parts required for that turbo."
Hiflowing usually only refers to a change in the turbine, not porting/polishing or switching to a hybrid setup. I've also heard of people keeping the existing stock wheel and just clipping it to improve the flow characteristics at higher revs. Obviously the downside is you have a slightly longer spoolup time, supposedly outweighed by a better breathing turbo.
Hiflowing is also popular because it can be done without affecting the insurance on a supposedly "stock" car, as it is highly unlikely any insurance assessors will know the difference.
taken from:
high flow turbo? [Archive] - High Performance Imports Online Forums
so what exactly is high flowing?
just upsizing the intake housing?
basically you have it one..............!
in an instace you want more power but dont want to change say many and got to external gate etc you can go for the hiflo options as it will all bolt straight back up and save you some money
tho obviously there are the direct bolt on jobbies but will depend on your application like the kk brand that otomot sell's for skylines etc
so for about 700 - 1k mark (maybe cheaper) you could go get the turbo flowed with steel wheels bigger in and ex housing wheels etc
vg30 nissan turbo hi flowed is a good example or the ct26 from toyota also full flowed would give you a 600hp rated turbo that bolts straight back on using t4 60-1 trim wheel
obviously you would still need other supporting mods with this like inj ecu etc to get the full out of it unless you stay a little on the tame side if you know what i mean
Matt