Just bought a stock evo8 I’ve been out of the game for about 15 years. Can somebody help me?

 

My suggestion is to go dig around the dyno results section and see what people are doing. Some of the tech has changed in 15 years but the recipe is the same.

Built 2.0
Large turbo
Fuel system to support that turbo
Supporting mods like exhaust, cams, intercooler, etc
Then the biggest change is probably to an aftermarket plug and play ECU

As my obligatory response whenever anyone asks for a specific horsepower number I will say this. Really think about how you are going to use the car and what you want it to be. Nothing is worse than dumping tons of money into a car to end up with something that doesn't work well for how you use it. If you are going to street drive it, 800whp is likely overkill and the trade off of reliability and response probably isn't going to be worth it. If its a drag car, thats a different thing and you will pick different parts accordingly.
Just really give it some thought, I'd hate to see you finish it and then its for sale because it isn't what you wanted.

 

You're in New York, take it to STM and let them build it.