Personally Dan, I wouldn't be overly worried using the 1/8" method. You should see better throttle response, slightly less smoke, maybe a tad of mileage improvement too. If you went/could go too high you'd hear the difference... . it would start to sound like the old Mercedes did... a hard distictive "rattle" sound.
Another thing that will tell you if your pump timing is set higher when you make the tweak is the way it stops when you shut it off. Instead of the engine doing what I call "the wet dog shake" it will pretty much just plain stop almost instantly... relatively speaking.
You can also raise the idle to about 1200 - 1500 RPM, hold it there for a few seconds, blip the throttle up a good shot then just release the throttle right away... the quicker it drops back to normal idle value the higher the pump timing... at least that's what I've observed anyway... .
There was a recall on some of the earlier IP's due to a potential failure internally that would result in a runaway pump condition.
The VIN number will tell you if your pump was one that was included in the recall.
My brother's 92 was one that needed to be replaced.
It's kind of ironic in a way... we are pushing these pumps so hard now that runaway is a possibility and we still don't "ease up" for the most part.
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