If you search around on this and other forums you'll find that you can boost the engines just fine with a good tuner, however the weak link is the Allison MH2500 transmission that your coach (and mine) is equipped with. It isn't reliable with more torque being put through it, from what I have read. Now if you had the 360hp cummins, it comes with the MH3000 tranny and it can take much more torque through it. If you do decide to give the Bully Dog a try or Banks etc keep us posted. I'd love to pour more power to mine but not willing to sacrifice and reliability at this point.
2008 Berkshire 360QS-40
"If you can't fix it with a hammer, you have an electrical problem"