Flex pipe placement
Since I'm making my entire turbo back myself I can put my flex pipe etc wherever I want, but I have some questions. 1) Where in relation to the exhaust/turbo manifold should it be located? 2) How much does length matter? 3) Does it matter if it's before or after the cat? (also related to #1)

I am assuming on Focus?? location just after oil pan and probably about 6-8" long?? just a guess on room in between oil pan and unibody.

Yes it's for a Duratec Focus, meaning the exhaust manifold is on the firewall side vs the Zetec where it's by the radiator. Any turbulance issues putting a short flex pipe immediately after my turbo exhaust elbow? So it would turbo->elbow->flex->cat->muffler.

remove the cat if you going to run a turbo. you would want the flex pipe on the downpipe. you can basicly place it anywhere on the downpipe where its straight. most people put them 6- 12" or so away from the flange where it meets the exhaust

I'm not removing the cat, period. Thanks for the placement advice though.

Don't put the flex section too close to the turbo outlet as it won't last very long there. Somewhere under the car is ideal, just as long as it isolates engine vibration. I have mine at the end of my downpipe, and it's a 6" long one. By the way- make sure you get a flex section with the "bellows" inside, the ones that are braided on the inside don't last near as long from what I've been told.