I was abe to reach a ranking of 24 before going into the Brain Tumbler for the first time. Woo-hoo!
I discovered that two Scavenger Hunt items I had previously thought were only reachable with Levitation, were reachable without it. I was always one-item short of completing half of the list (and getting the 4 rank ups) and always waited until I got Levitation to get the Scavenger hunt items I thought were out of reach.
I believe you only need one of these two items (see below) to complete half of the list. The Condor Egg is easy to get to...you don't need Levitation to get it.
Here's how to get to the Fossil in Sasha's lab...Raz is standing on the stairs in the middle of the room:
And here's how to get to the telescope in the GPC area...Raz is standing on the the boulder next to the boulder that is next to the little boulder that has the crow feather on it (so he's two boulders away from the feather). The GPC is behind him:
When you Double Jump to land between the two trees, you have to immediately Double Jump again to get up behind the tree and get the Psi-Cards. If you don't do the second Double Jump soon enough, Raz will start sliding down the hill and you'll have to try it again. Once you're behind the tree, follow the little "trail" that will take you up to the telescope.
By getting to a rank of 24 before going into the Brain Tumbler, you end up achieving the ensuing rank-ups sooner in each level so you're stronger earlier in the game.
I had mentioned in an earlier post that I thought the programmers had set it up so that a lot of areas in the game where you thought you needed Levitation to access, were actually reachable by Raz without it. This is more proof of that.
This is so freakin' exciting it makes me realize I have to get a life!
edited to add:
Regarding the second Scavenger Hunt item mentioned above (the Telescope), there may be another Double Jump involved. I went through it again last night and found that you Double Jump off the boulder to get to the tree area, then Double Jump to get further up the slope and then one last Double Jump from the top of the slope to land behind the tree where the Psi-Card is hiding.
I also found I could use the Double Jump to get the Psi-Cards on the lower tree limb on the giant dead tree in the Reception area (that has the fire ring next to it). This is the tree that has the Dinosaur Bone on it. If you Double Jump on the right side of the limb (facing the tree) you can bounce up off the tree trunk and Double Jump up again onto the tree limb. It's a heckuva lot more trickier than getting to the Psi-Card behind the tree (as mentioned above). The Double Jumps on the dead tree have to be a lot more accurate in order to get up to the Psi-Cards on the lower limb.
More proof that you don't need Levitation to get some of the Psi-Cards.