I set one up in my mk3 jett this summer using 2 1/4" aluminum tube. It sits neatly in front of the left wheel well; angled back slightly to align the fins with the air... I used about 4 and a half U-bends and it took me a short day to do. For the 90 that bolts onto the intake, the stock one was too small diameter so I just cut the flange off and welded a piece of my AL mandrel bend to it. Also, when I flipped the 90 around before I cut it, it was leaning too much towards the turbine housing; further prompting me to weld my own piece on.
For the oval connection-tank on the stock G60 air-air, I didn't want to screw around with that, and, it was pointing the complete wrong direction for where I mounted it. You can see the tank I build from AL sheet on the top side of the cooler. For the outlet of the cooler (the round connection in my case) it happened to be very close to 2 1/4" so I just went with that; on mine, I just used a foot of the rubber hose I had because I was too lazy to finish it with AL.
I can sustain 1300F pre turbine at 28psi in hot dry AB weather this summer so I assume the cooler is doing something good
Hope the pics help, if you got more q's ask away.
Peace,
Chester