Increase Boost, Banks Big Head?

The LB& Juice/Attitude will not read past 25.6 psi. The Juice will not allow overboost codes. You will need a mechanical gauge to read your increased boost. I have a very nifty KD Boost valve that will install in minutes and is fully adjustable. You will see quicker boost response/spool up and it is adjustable to provide as much boost as you want. It is compatible with the stock wastegate or the Banks Big Head.

Level 5 on the Juice with a stock trans is not a good idea...

You are correct. The early Juice was not exactly designed to be equipped with the Attitude. The revised #EJC 1001 was designed to read higher. The LLY Juice was built after the Atitude so it was equipped to read more. I don't think we'll see much past 30 psi though. I'll have to try it on my LLY once and see how high it will go. It won't be 99psi though as the sensor does not read that high...

No, the new model (nothing wrong with the old one unless it goes bad) is just different.