I think there are still a few people popping in and out who don't completely understand what the 19T upgrade to the stock turbo is supposed to accomplish. The whole point is that its an intermediate upgrade. Its going to provide more power than stock while providing better response than a 16G or VF39. Anyone expecting fantastic peak power and amazing results from a TD04L-19T is mistaken. Its not going to happen. If you want peak/high rpm power you need a larger turbo.
The big question right now is the 19T turbo from Performance Techniques. Two of us have been told that they use a TE04H turbine. One has been told its a TD04H turbine. There isn't a whole lot of difference between the two. In either case the result is going to be an improvement in high rpm flow. Both have a larger exhaust opening and will allow for a larger volume of exhaust gas flow. Obviously the TE04 is better for high rpm flow than the TD04, but both are an improvement over the TD04L.
TD04H = 2.04" inducer, 1.74" exducer
TE04H = 2.01" inducer, 1.88" exducer