Just giving my real-world experience with my 410 Stroker. Had complete stock setup with a plugged vacuum advance and then a full MSD- the ignition, distributor, coil, spark plug wires- the whole nine yards and did not see not even .001 difference at the drag strip.
Problem with those they fit so many specific applications so no guaranteed curve, say you order one for a 400 4 bbl you can be getting one for a 383 2bbl. They curve them in the middle if at all.
