as for experimenting with the pulleys i wouldnt recommend it as its an expensive game. the standard pulley will give you around 360hp at the wheels, the 3.12 will give you around 400-410 at the wheels but thats it on the engines safe limit. the 2.87 is only really safe to do on a forged engine or if you have bought a charger second hand from a a**hole in the US that cant hold boost! not thinking about any russian in particular . id say to go with the 3.12 pulley straight away as you might aswell