One of the levels at which suction performance can be increased considerably, is by increasing the magnitude and/or speed of the depression of the hyoid apparatus.  Furthermore, no mechanical interference can be expected between the size of jaw adductors and the lowering of the mouth floor by depressing the hyoid.  Therefore, if catfishes with hypertrophied jaw adductors need to increase their suction performance, modifications to the hyoid depression system are probably the most obvious option.  In this part of my research, I focus on the mechanics of hyoid depression and how morphological variation in the sternohyoideus muscle (the hyoid depressor muscle) is related to the way the hyoid is depressed.  The figure below (ventral view on the head) illustrates the difference in sternohyoideus morphology between Clarias gariepinus (left) and Gymnallabes typus (right).

Van Wassenbergh S.,Herrel A. , Adriaens, D. and Aerts, P. (2007).  Interspecific variation in sternohyoideus muscle morphology in clariid catfishes: implications for suction feeding. J. Morphol. 268: 232-242 full text (PDF)