Not sure what I should be setting my spark timing to?

The motor is a replica of a Haxby "EFI for everyone"

Gen 6 454 Mag
Standard Iron heads with Inconel Valves
Holley Terminator TBi EFi on a Victor Jr intake
Eickert Alloy headers with dry to the tip tails
Bob Madara custom hydraulic roller cam and full valve train

I am tuning it in the boat with the Holley software on a laptop and despite the dry exhaust reversion kills O2 sensors for a living so my tuning windows are fairly small.

It sounds good but doesn't pull nearly as well as I hoped so I wonder if I am conservative on the tune

My target AFR is 12.2-12.5 at WOT

I have been using 32 degrees of timing and today tried advancing it out to 36 degrees, it seemed to run a little stronger but I am worried that may be way to much and I could do some damage?

34-36° will be fine.

What was the performance gain over previous setup? I agree with Sutphen, 34-36 should be fine.

Are you in the rpm range at wot you should be?

Opinions are mixed but for the most part people have had good results using one of these on their O2 sensor to make them live longer.

If you have dry exhaust and reversion is killing the O2 sensors you may have other problems. I've been running wet exhaust for over 6 years with continuous wideband use. May be something to look into.

had same issue, tried a few extenders and filter no luck, moved the 02 to #5 header tube 10" from flange worked fine

I am running lightning headers wet with the inner collector extended 2 inches and a 525 cam. My O2 sensor lasted 2 seasons. Put mufflers on this year and killed it within 5 minutes.

You can watch the knock channel on the Holley for any Pre ignition if you have a knock sensor hooked up

Did you Dyno setup at all?

36* would be what I set it too with GM heads. 32-34* with a good set of heads.

call haxby,if your engine is a copy of his he should have the answer you are looking for.