PACE does a really good job of developing visual processing skills.
It also has a good auditory processing component. You might want to read some of my other posts further down on the bb. My bet is your son would enjoy reading a lot more if it were easier for him to do. In terms of reading comprehension, development of good decoding and visual processing skills usually takes care of the comprehension problem. However, if your son has good comprehension of books read to him, any reading comprehension problem is likely the result of poor decoding ability.