apex clutching questions and supertips

hey guys i was gonna order some supertips x series in the 55g base. whats the difference between the normal 55g weights and the 55g weights designed for turbo? the site doesn;t explain much.

secondly i have a shockwave helix and i've seen ppl running cat springs and such, why change the spring? i jsut have the stock spring but would a different spring be something i should look into? if so what do u guys reccomend?

thanks
spenser