how much extra do you trully want?with the internals of your 4k there is not much u can do.....dude...... going above 0.3 bar for your engine would be dangerous......any ideas on what is your standard hp output?any sifu can help me on this??i wan to turbo my toyota 4K engine..wat turbo can use and wat modifications need to be done..juz wan increse some extra power...