What noticeable difference if any will i find when not using the radiator heat shield compared to using it when participating in summer track days???? bearing in mind i only use upto Fifth gear and up to 13000rpm on straights.

Also people say lift the carb needles by 0.2mm, will it make a difference and what affect does this have on the position of the idle mixture screws when set at the usual 2.5turns out?