hummm,,,you know better regarding these engine..but as far i know
it makes complete difference when u doing 0-100 on 13s rim with almost zero traction issue
and then running 15s or 14s.....
on 13s its almost 4 to 5 cars quicker then on 15s in compare to d15 civic/altis/reborn
so it really change the results for me specially in 3rd gear when running against any vtec