User blog comment:B214/Question and Answers/@comment-9063800-20140112193808/@comment-16281343-20140112200903

Azazel already adivised Issei to develop a sub-species BB for Boosted Gear. As for that, there hasn't been any progress in that direction. He is more focused in stabilising and further mastering True Queen.

~For Sun Wukong's training, since there hasn't been much info about what kind of training they will undergo, I'll say that Issei's training will be more focused on his new body. Since Boosted Gear's weakness is the wielder's body.