It may, it may not, there's no hard and fast rule of when a spacer will give you more power. It's basically trial and error, but more times than not, it's a Band-aid fix for upgrades that may not be working together as well as they might, such as more cam than the heads can handle, or an engine with a too big carb, stuff like that. Since your combo is basically stock, a spacer probably won't do you much good, since these are all parts designed to work together in the first place. Plus, you have to realize that there are 2 different kinds of spacers, open and 4 hole. Open spacers are generally used to improve the airflow from the carb at top end on a dual plane manifold, 4 holes usually improve low end torque, and raise the carb up so the fuel doesn't puddle up in the intake plenum. Since your engine has headers added to it, a 4 hole MAY help now that you've opened up the exhaust. (Did you add bigger pipes as well to get the most out of those headers?). It may help, it may not do anything, It may actually COST you power, you'll never know until you put one on. Basically it boils down to are you willing to spend the 20 bucks or whatever to find out?