- rockers are the least amount of work, cheapest, and do the least

- a cam is pretty extensive install wise, but is cheaper than an intercooler and will net about the same gains as one

- an intercooler is an extensive install, but not a lot of motor work needs to be done


pulley size guessing is useless at this point as it really depends on your location, tune, and how healthy your overall setup is. you can assume that with any of this you can run at least a 3.2 with a good tune.