Getting these cars from the low 13's into the 12's is a major milestone.
I found also that the existing fuel delivey system needed to be upgraded at that point too.
I went from the 5/16 diameter lines to 3/8th, a Mallory electric fuel pump and high flow filter.
Those mods helped me over the hump.
Also I replace my orange box (ECU) with FBO's ignition box. Believe it or not, That change alone is worth 2-3 tenths. Well worth the 100 bucks it costs.