you may get it to run nicely, 9 times out of ten you will probably make it home. but it only takes that one occasion when you have your foot buried just a little too long, or the fuel quality isn't quite up to par and your left with a big bill. getting it set up by a decent tuner will allow for these variables and he will get the fuelling/timing spot on by monitoring the figures. setting up by ear is ok to get you to a set up, nothing more