"Not Quite Dr. Cliche's Underwater Lab" Revisited [UPDATED]

Know how much I hate overused tilesets? A lot. Therefore, I'm making a sort of revamped version of it.

Note that there'll be a few tile changes, so don't just stick it in your level, change tilesets, and think you're done.
Now, I need help, especially on the shading on the ends. Help?

EDIT: Updated 3/12/10.

I like the new shade of purple!

I like the new shade of purple!

Thanks. How you like the shading style?

Also, updated.

The shading for the tubes looks real nice.

The shading for the tubes looks real nice.

Thanks.