Quoting GSTwithPSI:
I can appreciate the work you're putting in. Is this just a personal goal for you? Just trying to figure out why you would go through all the hassle to install a turbo that flows less than a big 16G? I'm not knocking you, just curious. Maybe there are benefits to this that I'm missing? /ubbthreads/images/graemlins/dunno.gif
I really think it depends on your goals. You are right that this is a lot of work to essentially build a 16g powered car. However if you are willing to write that work/cost off and are happy in the 300-350 horsepower range of say a spirited daily driver then it nets serious benefits. With 'regular' 16g turbos getting both expensive and difficult to come by, this option opens the floodgates to a plethora of low mileage 'evo' turbos discarded by evo owners looking to upgrade and as someone mentioned whilst the flow of these turbos isn't massive, the possibility of twin scroll faster spooling turbos in the 16g power range is appealing to some.
I've got a fair sized collection of 16g, 18g and 20g turbos I picked up at good prices by being patient. But if I wasn't in that position, I think I'd seriously consider going this route for the daily. In addition whilst I wouldn't believe everything you read on the internet, someone on dsmtuners did this a while back and bought an 18g wheel rebuild kit for a twin scroll turbo and said it was the ultimate sub 400 horsepower turbo, power and torque everywhere in every gear. Maybe slightly exaggerated but again if you are happy in that 300-350 horsepower range I think the effort will pay the OP dividends. I'm certainly interested to hear about what he thinks about the finished results.