I was advised to buy a fuel to air ratio (Fast or Holley ) wide band O2 sensor hook up to tune in my carb. Does anyone have experience with any of these or recommend one over the other? I am getting black smoke and black plugs plus smelling like exhaust after driving the car. It's a 700 cfm Holley carb sitting on a 100hp nitros plate which is sitting on top a Weiand 142cid supercharger. My city and highway driving is horrible on gas and I am tired of the family smelling like exhaust after driving the car. any advice is appreciated.