A follow up on this post, the “strained” noise is still there. If the car is in 4/5/6th gear and I apply the throttle (but not enough to immediately engage a kick down) the car stays in gear and accelerates, but there is an odd noise coming from the transmission. It feels like an extra load is going through the transmission, almost like it is struggling. Odd to describe, but imagine the noise you make when lifting a heavy object, that internal “ggmmrr...” noise. That’s what the car seems to be doing! So, I’m worried that is the either the gearbox struggling to transmit or the torque converter is under extra load. The car is on 84K so it might be needing a change of gearbox fluid and filter, possibly. I’m going to fit the bypass plug and see if the car does this in normal tune, certain it didn’t before the box was fitted. Can’t think it is a turbo/injector noise or issue, possibly a HP fuel pump?