What didn't gain me much if anything was removing my 12.5:1 340 and installing a fresh 10.5:1 408 with W2's. It was seat of the pants only, but that 340 sure felt quicker than that stroker in the early days of it. converting from SS springs to caltracs, switching 4.10 gear for a 4.30 gear with a loose vert. and replacing my 950 holley for a 1100 Dominator when i had a small block. I never made any big gains with one component change. It was a bunch of small gains that worked in the end. Switching from a 10" 3500 vert to a 8"5200 vert made a gain. Switching to Hoosier QTP from the old M/T drag radials made a gain. I now use the M/T ET street R and its better than the Hoosier QTP. Installing a crank trigger made the timing rock solid, so it was a gain in accurate timing. I don't remember seeing any gain at the track, but accurate steady timing is always a plus.