Will I notice an improvement if I get a better cable for my sub?

[SicilianKing]

Right now I am using the stock cable that came with my HTIB system...would I notice an improvement if I got a thicker cable for the sub?

[ElevatorHappyFun]

the cable you speak of, is it speaker wire (non powered sub) or a RCA (powered sub) ???

speaker wire - yes, get thicker. HTiBs are notorious for using EXTREMELY too thin of wire.
RCA - monoprice.com will be your best friend. you can get a cable as good as monster for 1/10th the price.

--edit--
placement of your sub is just as important. since the wavelengths are so big they can get a little wonky in rooms. try having a friend move the sub a little bit. also the tip of the day for subs is.... Turn the sub at an angle to the wall.

[SicilianKing]

hmm at an angle to the wall? Have not heard of that one..I placed the sub in the upper left corner of the room..and have the front left speaker on top of it...

Oh, and the sub is RCA powered..