pipe run length can be seen here, i dont think its long to be honest, probably shorter than most. The turbo to IC inlet run will be 6" longer i guess due to top mount now rather than the picured stock position.
I havent bought the cooler, but theres a few i have my eye on and theres a choise of 2.5 or 3"
2.5" suits me as itll be lighter and easier to package as there aint a lot of room under the bonnet anyway (when its on the car
) but dont want to use 2.5 if theres a possible restriction
EDIT running KA24 TB but cant remember the outer diameter