Hi guys here is the real truth you don''t need to re-jet a harley davidson stock carb ,they are great but here is what you have to do . About stock mufflers you don''t need to change them . All you have to do is get a real long drill bit . To check the lenght that you need a wooden stick and see how far it goes in then you have the correct lenght of your drill bit you don''t even need to take off the mufflers . The louder you want it the thicker the drill bit.About the carb you will have to take it off on the bottom there is a lead slug which covers the carb adjustment screw . After you trun the screw all the way in turn the screw counter clockwise about 2 and a half turns out . Now you have a good starting point .You will notice the improvement .Guess what no more spitting and coughing . JUST REMENBER NO MORE IDLE TIME FOR 5 MINUTES. After this is done just adjust the idle screw because it will idle to low . 1050 rpm is a good setting use your tack. About the air box . Use a K&N AIR FILTER NO NEED TO CUT THE STOCK AIR BOX . This was don to a stock sportster 2003 xl custom.The bike now has a great sound and still street legal you had enrichned the carb . the carb is set too lean at the factory . I hope the will be some help .MIKE D . Tis is what the performance don''t want you to know then they charge you big bucks for BS.