The old coils were set aside, and the Performance distributor coils were put on top of the old Champion plugs with the factory .040-inch gap. Since so many people replace the plugs and the coils at the same time, we wanted to eliminate any change being the result of a plug swap or gap change. With that set-up, the Hemi Charger spun the dyno wheels to 313.2 peak hp (at 5,150 rpm) and 345 peak lb-ft of torque (coming at 4,200 rpm). We were up 10.2 hp and 8 lb-ft over the baseline—that’s a difference most calibrated butts can feel.
Next, we gapped our new Autolites to .065 inch, torqued them in, and put the SOS coils back on. The idea was to see what kind of gain most people would see all-in, with new coils, new plugs, and bigger gaps. With the new coils and plugs, the Charger was again run on the dyno for three runs. The SOS coils and new Champion plugs pushed the peak torque up to 347 lb-ft at 4,250 rpm, and the horsepower jumped to 314 hp at 5,150 rpm. The peak numbers were up another 1 hp and 2 lb-ft from just the coil packs alone.
This is from HOT ROD magazine website. they used a 5.7 on a charger, with SOS coil packs. Tested first with a spark gap of .040 (stock), then changed the gap to recommended of .065 for the new coil packs. They did get a jump in power.. not sure if $400+ average going price is worth it..
