Temporary exhaust system

(whiny, manipulative tone) Would it really be thaaat loud?? (LOL) I think before I make a decision I'll break the engine in with no exhaust and see how loud it is. If it's that bad I'll just say hell with it and hook up the stock exhaust for a while. Also, do you not recommend the flex hose procedure just for sound, or would it also be bad for performance?