I have a 2006 Heritage Softail, I have Vance and Hines drag pipes, I had bigger jets put in the carborator and a thunder max box put on it. Now it coughs. I have taken it to all the Harley Davidson Dealerships in my area, they say that they fixed it, but it still coughs. I have taken it to a couple of no name shops and they say that it is supposed to do that... I took it to the representative of Thundermax and he said he fixed it but it isn't fixed. I have never had this problem until I put the Thunder Max in and I only get a 140 miles per tank. Do you have any suggestions? Thanks!