Does anyone know what the relative weights of different string types are? For the same gauge in the same racquet. Like, "average syn gut in 17g is the lightest; average multi in 17g will add "x" amount of grams; average poly will add "x" amount of grams; and average NG will add "x" amount of grams". Reason I'm asking is I have 2 K90 that both weigh spec 12.0 oz unstrung. Both have overgrips. The one with syn gut (Gosen OG micro 17) is 12.55 oz. But the one with multi (X-1 Biphase 17) is 12.75 oz. Is this normal?? ... Hmm...it had been really humid here a couple weeks ago.