Not reallyThe only way to keep as much detail as possible is to size it on your aircraft and then go back to the original art and use the <image size> window to make your nose art the correct size. It will be a little sharper than if you drag the art on to your plane and resize the object that way.
The other way is to make new simplified art and reduce it...but that's a lot of work.
You can also try the sharpen tool but you'll only want a small amount of sharpening so right after using the filter, fad the filter by a percentage, 30-40% maybe.
That's as much as I know, any other tricks guys?