Can I attach multiple Bixpy Jets to my Kayak or SUP?

Yes and no. We have tried this and the results are not spectacular. As mentioned above, there is something called "hull speed" for all watercraft. This is pretty much the maximum speed something moves through water no matter how big of an engine you put on the back. Depending on how scientific you want to get, you can Google "Hull Speed" and really get into this topic but essentially, the only way you can go faster is by getting a faster kayak or SUP. Those tend to be the longer and more slender kayaks and SUPs used for racing. Regular kayaks (like Hobies, Pelicans or Preception kayaks) will top off at about 6 MPH with one or two motors. Keep in mind, this is all based on perfect water and wind conditions. The truth is, wind, wave and water conditions will usually prevent you from reaching your hull speed, so putting two motors on your kayak will only help you reach that hull speed more quickly and more consistently regardless of the conditions. The big question: "Is it worth it?"  In our humble opinion, not really. Although it's a bit more fun having the extra push, you'll find in the long run, it does not make enough of a difference to justify the purchase. One thing that you will likely find useful is an extra battery pack for long days out on the water.