i have an ls with i/h/e and im thinkin about getting a bigger throttle body and intake manifold. Does anyone have any advice? How much hp should i expect to gain?

Don't waste your $ unless you go forced induction or an all motor build. The stock t-body and IM flow efficient enough for your current setup. Chances are you will actually lose power with a new IM and t-body. There is a need for something to push and make use of the air,

save your money and buy cams. i went down that same road and lost money.