Though the stock tips are good enough, i kind of like the wide bores and i enlarged the nozzle with some blue tac. Now they sound fantastic! Idk but i find the trebles to sound smoother (perhaps more space to push through xD) as it was a tad bright after removing the foams under the mesh.
Idk the science behind the bore size as i feel wider bores reduces bass and increase trebles, but narrow bores increases bass and sibilance. Either way the stock tips wont go to waste (actually i lost one side when i was out the other day, dang) as they are fantastic on the CCA C10, TRN IM1 (L) and KZ ED9 to name a few.