Because I'm running the Rokktech sensor, I can't run anything that increases cetane (timing ping). I found that Howe's doesn't increase cetane like PS (which I ran for a long time), so I run way more than the recommended dose in every tank (I don't measure, just dump about 1/4 bottle per 25-gallon fillup)...
To date I have had no issues with timing advance and running Howe's...
I ran PS through my 99 almost exclusively with a couple runs of Lucas, and both worked equally well...
steved