For all you good bowlers out there i have a ?

I am looking for a new ball. I throw a straight 13 pound ball now. Its a plastic ball, actually i guess I was wondering if there was any other kind of ball besides a plastic ball that i could throw a straight ball with or if that would make any difference in trying to bowl better. I leave alot of splits. I was throwing an 11 pounder and switched to a 13 thinking that more weight would make me less prone to throwing splits, however i seem to be bolwing worse lol. I know that are not plastic are usually used for throwing a hook...but would any of them work for throwing it straight too?