It's like ping pong up in here! Forgot to say It will be ok to tune to the pipe if you just want to scoot. When you do change out the box you will have to open the jet a little more, but you will have an ear for it by then, and it will go much faster. I can generally set the carb. w/ three attempts. First to get a ball park idea (rich-lean) second to find the other limit, and third to tweak it. The more you work at it the easier it becomes. Plug chops are the key. once you think you are running pretty good, get 3-4 new plugs, and do a few runs to verify. Even an EXPERT ENGINE BUILDER would not run an engine w/out a few chops to verify the cyl. temp