Turbo timer will void cat 1 spec.
TBH they are a waste of space imo, if you need to let your turbo cool down as you've just been thrashing it just sit there in the car.
All I do is for the last mile or so is make sure I take it easy, with the engine running and the car stationary it is soaking up much more heat than just shutting down, as it gets hotter than it would otherwise have been, that's my view.
tabetha