The TA is a so-called stock appearing turbo. The compressor cover (housing, scroll) has a small inlet, necessitating the use of an adapter (bell, reducer), which takes you from MAF duct size down to compressor inlet size.
With a TE, the MAF duct attaches directly to the compressor inlet. Lose the bell. Lose the gasket. Lose the 2 nuts. Eliminating the bell results in less pressure being lost due to fluid compression. Pressure loss at the suction of a compressor operating at slightly less than atmospheric pressure, as is the case with turbochargers, represents an EXTREME DRAG on performance. It the same reason we use big, open air filters, bigger MAFs, straighter, shorter, smoother ducts, and the like.
A TE44 has the same compressor wheel as a TA49, the difference being that it's cover is optimized for the wheel. Ergo, higher flow and HP capability.
Opting for a smaller than optimal compressor cover is about as clever as carrying 500 pounds around in your trunk for fun...
For some reason lots of folks don't get that???
Oh, and there are lots more little differences between a 49 and 44 that most folks have no knowledge of and would swear otherwise. If you really want to get educated on all the nuances of these 2 turbos, spend a few minutes on the phone with John Craig at Limit - he'll be happy to run them down.
Good luck with your build-up!!!