it isn't as simple as just useing forged pistons....to have an unrealistic goal of 800 hp than you should atleast have a clue what turbo will get you there.
Advice...set a realistic goal of around 350hp...when you reach that, by then you should have a clue what it's gonna take to get your 800! Just so you know, the people here who have reached the 800hp mark probably spent so much money to get there that they could be driveing a dodge viper....and they know it....think about that...power isn't cheap...and the more you want the more it will cost you...
For example...IJ here has about $7000 invested in his headwork alone!! He is around 400hp....$7000 fucking dollars.....I'd probably shit out my mouth if I knew what his bottom end has invested in it.....not to mention his standalone and all other fancy shit he has to keep his moneypit moveing....
Good luck...but with good intentions I say "get real"!