mods dont really add to the value of the car, unless you find a buyer who wants a car with what you have and doesnt want to do the work to it.
you can add 10k into mods in a 15k vehicle, itll make it worth maybe 16,5-17k. mods are done to a car because you like modding, not like a house where you can renovate and it adds equity.
Agree with these guys, putting in a forged motor isn't really going to help value. If your planning to sell it soon, just put another gt motor in. If keeping it, obviously go with something bigger/better, but don't expect to add value to the car.