Who here is good at reading spark plugs?

Rat Bastid said
You have to tune to the leanest cylinder. You may have to live with that depending on your manifold and some other things like overlap and how well your headers work. You need to look at them all and make sure you know which plug came out of what hole and find the leanest one. And tune from there. And you have to check every plug, every time. When there is excess fuel blowing around in the intake any change you make may change the distribution characteristics.

If you have port EFI then you should be able to clean it up pretty good.

Thanks for the advice, much appreciated!

The Holley Sniper acts like a carb in that the fuel/air is combined in the "carb body" itself before it reaches the intake manifold for distribution to the cylinders. So whatever changes I make to the mixture will affect all cylinders.

If I understand correctly, Port injection sprays fuel into the intake port of each cylinder making it easier to adjust A/F mixure to a particular cylinder.

I'm running a Weiand intake and Hooker headers, Edlebrock heads. I'll pull all the plugs and, like you said, tune for the leanest one.