Things you did/upgraded that surprised you how helpful they were

going from spreadbore intake and carb to square bore made more of a difference than i thought it would. intake was an ld340 that i ported to accept a holley 800 double-pumper spread-bore carb. the same intake with a 750 double pumper saved nearly 2 tenths and gained 3 mph in the quarter mile. my 340 went from a previous best of 12.70 to 12.51 through the mufflers at the time.