Dang, a throwdown and I missed it.
Dave's right, folks. Most additives, fuel injector cleaners, etc, aren't worth the bottle they come in.
Lead additives are arguably the exception to that, but it still makes precious little sense to use 'em. The ONLY excuse for using them is because of valve recession, which is pretty much a non-issue, since hardened seats have been installed as a matter of course for more than 10 years now. If your head has had any work done in the last decade, you've got hardened seats. And even if you don't when (if, really) you ever have an head work done, they're going to put hardened seats in. And the work will cost you less than the endless cans of lead additive you've dumped in the tank in the meantime.
Other additives aren't worth a plug nickel. They don't do diddly.