Could u please tell me if i have to adjust the fuel ststem on my yamaha xvs v star 03 after installing jardine slash cuts whitch do have a baffle

Yes , to get rid of the flat spot that you get from opening up the exhaust system, you will have to put in a jet kit. Cobra and Dyna Jet make make good kits for $60 to $100. Another product replaced at this time is the air filter. A K&N air filter will create more air for better breathing.