How much do pickups change the sound of an electric guitar? Performing Arts?

I have an Epiphone Les Paul standard, I guess not the best stock pickups in it. If I changed each of the 2 to EMGs, 81s or 85s, like kirk hammett, would it dramatically change the tone or just a little? i play rock and heavy metal. i have a line 6 75 watt combo amp. i don't want to waste $200.