HI, i have a 400ex with a dyno jet kit, white bros pipe, and white bros air filter. if i wanted to put the stock pipe on for riding it around my house. would this affect the jets or do any harm? thanks please get back to me

 

I dont think it would affect the jetting too much. Just try it and ride around for a day then check your plug. I really dont think it would change your jetting too much though.