I had a Toshi chip put in & it made decent difference between 3800-7000. Felt stronger & more responsive. It was $250 for the chip fitted to your ECU or $350 to by a chipped ECU outright. What you get out of it depends on what mods you have to an extent. Mine's just got an RB25 turbo, 3in turbo back exhaust, filter & R33 GTR fuel pump.