I have a ka24de (*edit 205,XXX mi). i used it a few times when i first heard about it awhile ago, but haven't used it in my past oil changes just because i forgot about the product.
I feel that it did work when I used it and it actually did keep my engine in better shape after (less noise, better mpg and power, better response). Even now, a few years later, I feel like the engine is running better than it did before I used the product. I probably only used it 3 times straight. I might do it again on my next one just because :P
Read this thread on hotrodders.com
Engine restore Does it work?
I just google'd it and there are some pretty bold claims that might make you want to just try it for yourself. There was even a guy that received a blue ribbon at his state fair for doing tests on it, but then again, it was in iowa. lol