With the X-15, the wake just keeps getting better - the more weight you put in.
I regularly have about 3000 lbs in my X-15 and it is awesome - stock ballast with fly high X-star set up on top of it.
To have it all ballanced out, I typically fill the back sacks only 2/3rds.
Occassionally, I fill the back all the way and throw an whole extra sack in the bow. With 4 guys in there, it is probably pushing 4000 lbs.
Those are the days when I make sure to bring out a camera.
When I have that much weight, the wake is huge. It is really fun.
I save the 4K to special occasions - because the next day I am usually pretty sore form landing all the huge airs.
It is just important to have all that weight balanced correctly. If you have people sitting in the back, you will need to compensate with even more weight in the bow. If you have too much weight in the back, the boat will drive poorly and you will have trouble keeping speed. Sometimes, it is just a matter of one person moving forwar a bit.
At 3000lbs and lower, it isn't so finicky. Once you bump into the 4K range - weight balance becomes really important.
I have the trim plate on my X-15. The trim plate really helps when starting out.
I trim it all the way down to get the boat out of the hole. Once I am at wakeboarding speed, I have the trim put all the way up - which makes the wake perfect.
If you have the trim plate all te way up - you might never get up with 4k lbs in the boat.