FG F6 injectors are sh1te. They don't flow enough for good power and are probably at max duty cycle. To maximise fuel flow you'll need: - Larger injectors, some Seimens 60lb injectors for example - A larger intank fuel pump like a Bosch 404 or Walbro To fix the wastegate issue and allow the tuner to control boost better: - Get a 12psi actuator installed - Make sure the wastegate has been ported and a 38mm swing valve (flap) has been installed. Otherwise the boost will spike and could cause detonation (pinging) A retune should get you a lot more power with those things sorted, but your cooler will not do the job and you'll cop heatsoak as the cooler will not cool the charge air enough which will rob a lot of power. A better cooler and piping should be your next upgrade. With all of the above and a cooler you should easily see 350+rwkw on safe boost (15-16psi) No matter what BOV you use you'll always get the surging sound. Many, many, many people have blocked the BOV off for many, many, many years and never had a problem. Surging hasn't been proven to blow up a turbo so it's all about the sound (or lack of) that you prefer when the throttle shuts.