Well, they both use custom housings, and swapping a wheel takes no time at all. The difference between them, is simply the size of the compressor wheel. Thats all. The 20G will hit MUCH harder, and spool a little slower, where the 16g will spool faster, but doesn't pack the same punch.
I personally like the td05H 20g myself!
Chris Boone
Slowboy Racing Inc.
cab@slowboyracing.com