no such thing as an EX-V. but there is such a thing as an EX sedan. im pretty sure all EX civics are factory Vtec cars.
there isnt any way for us to tell what transmission you have. but its easy for you to find out
Look around the fill plug for a circle cast into the housing.
A000 = DX, CX, VX trans
B000 = Si, EX trans
itll look like this
if it isnt an EX/Si trans then swapping one in will not actually make a difference in horsepower. buuuut it will give you shorter gears, quicker acceleration, and just make it more of a peppy car.