Because the K03 pipes contain the O, and the K04 turbo inlet holds the O. The difference between ID and OD of the O ring makes it a perfect fit. Just lube it up with some engine oil and slide it on.

I did get some from a local HW store, but the K03 ones fit better and were made of a nicer coated material.

ASP Stage III and stuff ;)





Caveat: Any advice I express regarding potential tuning and such is purely informational. If your knowledge and abilities are not up to the task, no amount of advice can assist.