Taking 3-4 pounds of cables out and put 8-10 in. A whopping 5-7 pounds if using 1/0 welding cable like I use. Go on a diet! I guess if you are a stock or super stock racer looking for every hundredth, that might be important.
i wouldn't be the slightest bit worried about adding 20~30lb to a street car. if you're competitively racing for money where hundredths count, different story.
dudes be out there: i need to be as light as possible and i need another 100hp to knock a few 10ths off. drop 50~75lb and take the $$ you were gonna drop on mas HP and put that into better tires or chassis tuning/mods and betcha that picks up half a second instead.