I ran 14 degrees initial timing on my old combo with a NX 150 shot and Autolite 23's gapped at .035 (11.70's)
I run 26 total on the new setup (10 base+timing added or sub. through the PMS handheld) with NGK R5671A-9's @ .035 (time in sig)
What was your bottle pressure on the passes you made?
Pulling timing may or may not net you some ET... that's what tuning and finding what your combo likes is all about... test 'n tune and see what you come up with and let us know...
...and do what 87gt recommended as far as reading your plugs... shut the motor off as soon as you cross the 1/4 and coast off to the return road and pull your plugs to see precisely what's going on while under power... is that how you've been reading your plugs?