What are the average gains e.t. wise when adding a 4c and baic bolt ons? I know a guy who has a 4c converter basic bolt ons( cat delete, cold air, ported stock intake and tune of course ) but he is only running about a .10 faster than times I was running 2 years ago with no converter. We both have the same setups I just had a couple more suspension parts and 4.10s. I'm a base model he's a premium but he's only about 200 pounds heavier than me in race trim. Right now he can only average low 12s with a high 11 every now and then. Our cars a almost identical other than the few parts I mentioned. I know every car is a little different but I'm thinking something else is wrong somewhere with his car. And we trap the same mph
