Не все так просто в царстве  
 
 
TDO4/TD05/TD06 - TURBINE WHEEL SIZE - H,L,HL designation also affect the size but I'm not certain how. I know for a fact that a Td04l is a larger turbine than a td04, and that the td05h is bigger than the td05/ 
15G, and 19T are the compressor wheel sizes. 
Here's what I have seen with regards to blade spacing and compressor sizing. 
- smaller numbers are smaller wheels. 
- I guess that the letter designation is related to the inducer/exducer ratio (Trim) 
9b,11b,12a,13c,14b, 15c,17c,and 19c all have the same size blades. Basically A,B,C and D blades are even. 
G, K, T wheels have staggered spacing - I would assume that K and T wheels are newer designs, as I haven't seen them on older models. 
G, and K wheels flow more in the top end than A,B,C,and D wheels. 
EG: 14B flows less than 14g, 15c less than 15g. 
I think the K wheel is new because a TD08 26K flows more and more effieciently than the td08h 33D (AKA T88H) 
Final assumptions based on the above: 
- Smaller turbines will have less lag and less top end. Top end can be improved at the expense of lag by getting a bigger housing (EG 7cm vs 6cm) 
- Small compressers = Less lag, and less top end. 
- Staggered blades = More lag, better top end.