[Scott.T]

Andy Forrest's is a 20G, just with his own branding and fetling.
20G will be a good choice on the TMIC, MD321 a better one.

I'm not 100% up on the compressor maps for the 2 turbo's but assume the MD321 is larger.
The TMIC flow and cooling efficiency is better suited to the slightly larger turbo as you can run less pressure for the same HP, due to the greater airflow from the larger unit.

Too much pressure on the STi TMIC will split/blow the intercooler at the crimpings.

Both turbos will have a good resale value if you decide to move on at any point in the future.

Sump is overkill imho, if it were a 100% track tool doing alot of track work then maybe a consideration.

Harvey Smith also supplies 20G's for around £750.