Bought a boost leak tester from Markski (works great btw) and hooked it up and immediately found a giant leak where the lower boost hose meets the intercooler. I couldn't add more than 5 psi and that lower hose wanted to pop off and you could hear it leaking. To save time and to order the right part the first time, should I replace the entire hose or just the O-ring?

 

Check the tabs on the hose. They tend to get pushed in and deformed which makes it easier to pop off. Simply taking a small screwdriver and pulling them out a bit would help it to stay where it should.

 

It is really important to have the proper clip in the proper position. You can found more than 7 different size of those clips on the TT. (99610680211 99610680210 99610680212 99610680215 99610680216 99610680217 99951231700) Some of them are really just a bit bigger or smaller and if you put them in the wrong place it will pop out... If you look at the picture you will see they are similar but different part#!!!!