Yep, the upper is the weak link. I have the same boat as you, 29 fever with the single motor. With the motor upgrades done to the 575SCi I can get on plane with only 1/3 throttle.
A lot of guys break the drive around 3000-3500 rpm’s with it trimmed down and plowing in rough water (wet hull). Around that rpm is where the torque peaks and is hard on a drive.
Try All American Drive Service here in Michigan. Good guy to work with. Also Mr. Gadgets is the man.
It’s no fun standing on the beach or being towed in. Put extra cash aside for an SCX or Bmax first and you will be at ease without the feeling like you are going to break a drive every time you go out. “Been there done that”.
That’s what I should have done before I spent over 10k on rebuilding 3 Bravo’s.
The Bmax is almost a direct bolt on. Did mine in a weekend. The inside parts in the lower is the same as a Bravo but I never had any problems with the lowers. Cryo gears from the Bravo Shop and a good setup and you should not have any lower issues.

Thanks for your input. I've been hearing more about the Bmax drives and am thinking I need to start looking into them more. I full intend on an upgrade and that seems to be right up my alley. Seems that might be the best upgrade for the cost??

You need a different prop if that is what you're after. Its not a ski boat and its not going to jump on plane like one.

One of the things to keep in mind with fountains is , (from what i have taken) is majority of them are set up for top speed, your X dim may be a little high in order to achieve this. You wouldn't be the first fountain owner that has trouble getting up, but once it does it runs like a raped ape. check with some people that are knowledgeable about your hull just so you dont start throwing money add it. would a spacer help with coming up on plane? maybe a diff set of props? As Mr gadgets said, torque is what kills xr's. my boat is a heavy pig, but i have only broken a lower gear and that was at 472 hours. I guess my point would be is try a few things that address the problem, not the symptom.

I was informed about the fountians slow plaining before I even went to look at the boat and you are right about "raped ape", once the boat hits plane it takes off like you hit a NOS button! I guess I should clearify to everyone too that I do know there are plenty of other ways to help getting the boat on plane rather than spending the $ and installing a SC! BUT, I've been a gearhead my whole life and I cant leave anything stock and love HP and speed. I usaully am good too about upgrading the weak points 1st before up-ing the HP. Im just planning on running 4 lbs on this motor until I upgrade the lower unit.

I can understand being a Gearhead myself and how we love to improve everything! I love my Prochargers and love the speed also, but hate the cost and downtime! As long as you are aware then have at it and enjoy. Just would hate for you to not realize everything and get a bad taste for high performance boating, or get in over your head which causes you to get out of boating in general. Theres just something about once you have the speed if you end up not being able to afford it and have to step back down to a slower more reliable boat sometimes it just causes people to get out of boating all together.

Yes your engine will handle the blower for a while on mild boost. Just as long as your aware eventually you will either need or want to upgrade

Bravo drive will handle the added power for a while on mild boost. Just as long as your aware you will get sick and tired of babying the sticks even if it does not break.