Was driving around earlier on and come across yet another problem. Pulled out to over take a car in 3rd gear, as the engine hit somewhere between 5-6rpm there was a pop sound and the car felt like I had slammed the brakes on. Came off the throttle and eased it up to a roundabout. Had it in 2nd gear and put my foot down, no issues until the same sort of rev range. No pop this time but lost all boost and again, felt like I had slammed the brakes on. Was dark by time I got home so could only have a quick look with a torch, couldn't seen any boost pipes out of place. Any thoughts on what this may be?