I've always been on the hunt for amazing crystal clear headlights that look brand new, so I've tried everything and anything I could to brighten mine up.
So from my past experience, I've found the ultimate solution. Please don't read on if you hate disappointment.
What you'll need:
Toothpaste
Sandpaper, 300grit-2000grit
Water
Elbow Grease
Run-of-the-mill headlight cleaner/restorer
UV Sealant/protector
Coca-Cola
What you do:
Take the toothpaste, sandpaper, water, headlight cleaner and UV protector and throw it away.
Drink the Coke and buy new headlights.
This is my car after using every possible solution to clear them up:
They looked great, but not by comparison. They're still faded and dull. [This picture makes them look better.
After I got clear corners, they stood out really bad.
So I heard of that UV protector crap, and after another 4 hours clearing the headlights to a mediocre "clear", I applied some of that stuff.
Three weeks later.
They yellowed even more than they were before. I at least had them white and foggy at one point, I think.
So I gave up. I couldn't see crap at night though, the Tbirds lights are not that well designed.
So I finally got new housings.
I had the same issue with my Taurus. [Before I got two new headlights for a retrofit] One of the lights got busted, so I bought a new one, well that other side was always noticeable no matter how clear I got it.
In the end, there is no replacement for....replacement.
So from my past experience, I've found the ultimate solution. Please don't read on if you hate disappointment.
What you'll need:
Toothpaste
Sandpaper, 300grit-2000grit
Water
Elbow Grease
Run-of-the-mill headlight cleaner/restorer
UV Sealant/protector
Coca-Cola
What you do:
Take the toothpaste, sandpaper, water, headlight cleaner and UV protector and throw it away.
Drink the Coke and buy new headlights.
This is my car after using every possible solution to clear them up:

They looked great, but not by comparison. They're still faded and dull. [This picture makes them look better.
After I got clear corners, they stood out really bad.

So I heard of that UV protector crap, and after another 4 hours clearing the headlights to a mediocre "clear", I applied some of that stuff.
Three weeks later.

They yellowed even more than they were before. I at least had them white and foggy at one point, I think.
So I gave up. I couldn't see crap at night though, the Tbirds lights are not that well designed.
So I finally got new housings.

I had the same issue with my Taurus. [Before I got two new headlights for a retrofit] One of the lights got busted, so I bought a new one, well that other side was always noticeable no matter how clear I got it.
In the end, there is no replacement for....replacement.