Both standard and "balanced" injectors are available form TCM for the 520 and 550. About 30% of the balanced injectors are "balanced." TCM cannot tweak them to be balanced like GAMI can on theirs. Comparing TCM's "balanced" injectors to GAMIjectors is a very poor comparison.
If, OTOH, you get lucky and get a good set of TCM balanced injectors… good for you.