Dexter makes a 2-5/8ths and 3" lift kit for Torflex axles.
You can find the installation instructions here: http://www.dexteraxle.com/i/u/614960...x_Lift_Kit.pdf
I also found an aftermarket kit listed on Amazon, but it's an old listing
Dexter Torflex #11 Torsion Axle Lift Kit - Amazon.com
Looks like they're made by this company in TX. They offer a $79 kit for #10 axles, but I didn't call to see if they have one for #11. I assume they do becuase the Amazon listing was for #11. I imagine the differences will be a thicker sidewall block and 5/8ths hardware.
There is a way to get a higher ride height without just ordering new axles with a higher start angle. This would actually be a better option because you can keep the the loaded arm angle at a more desired 0 degrees.
Disclaimers: (or frankly, don't waste your breath)
1. Raising your Airstream will raise the CG (center of gravity).
2. Raising the CG will contribute to inducing sway or PIO (Pilot Induced Oscillations).
3. Raising the CG will reduce emergency handling characteristics.
4. Raising the coach will increase air resistance and decrease fuel economy.
5. Raising the coach will most likely require raising the TV ball height accordingly.
6. A lift kit is no replacement for warn out axles. If the rubber has solidified in any torsion axle it should be replaced.
7. Raising the coach may require adding another step so Great Aunt Mildred can get inside.
8. Lifting an Airstream could induce scoffing from Airstream traditionalists. Mutterings of "Clown!" and "Humph!" could and may be heard under-breath.
9. Some Airstreams need to have the undercarriage tank protection skins modified for clearance because there is some interference with the axle bracket.
10. It should be noted that the pictures listed here are for regular mounted bracket orientation. Airstreams use "reverse" side bracket mounting which would make threading the side bolts into the nuts inside the block kind of tricky.