The new airbox snorkel found on the Focus SVT has a much larger, smoother cross-section than the base stock Zetec snorkel. The following instructions will allow you to cleanly install this snorkel on your Focus, and your engine will breathe better as the result.
1. Unplug MAF sensor and loosen hose clamp on MAF.
2. Using flat blade screwdriver, unbolt top of airbox and remove. Remove filter.
3. Using phillips screwdriver unscrew snorkel inlet from radiator support and remove "screw" clips.
4. Pull bottom of airbox out of engine bay. Disconnect old snorkel from airbox. Note: the old snorkel fits inside the airbox opening. Keep in mind that the SVT snorkel will fit around the outside of the sleeve on the bottom of the airbox housing opening.
5. Grind off the four reinforcing tabs on the airbox opening sleeve until flush with sleeve. I used a flat file, but a dremel would be handy for this.
6. Slowly heat the airbox end of the snorkel and coax it into a round shape.
Note: Step #4 is the most difficult step of the process. The SVT snorkel is triangular on the airbox end, and it needs to be round. Once it is round, it will fit tightly and perfectly around the airbox sleeve. I used a gardener's bulb planter tool to do this, because it is round and tapers gradually. As you heat the end of the snorkel, twisting and forcing the bulb planter into the end of the snorkel will coax it into a round cross-section.
One problem I encountered was with the plastic piece to be heated. It is actually two halves snapped together and as you force the end of the heated snorkel into round, these two sections want to separate. To counteract this separation, I used a hose clamp to hold two halves together.
7. Once the snorkel is round and still warm, fit the snorkel over the sleeve on the bottom of the airbox. It should fit completely over the sleeve. Allow to cool. Note: You may use a hose clamp to fit the snorkel to the airbox, but mine fit so tightly it wasn't needed. I did, however, leave on the hose clamp holding the two plastic halves of the snorkel together.
8. Re-install snorkel and airbox in car, and enjoy. Note: Small angle adjustments may be needed on the snorkel when installing into the engine bay. At the angle I used, the small "V" looking tab on the snorkel did not align with the grommeted hole it is supposed to fit into. I cut off the "V" shaped tab. Also, the snorkel may rest on an exposed stud protruding from the transmission mount. I solved this problem by threading a rubber vacuum cap onto the stud to prevent the stud from wearing a hole through the snorkel.
I've been checking mine periodically over the last 1000-2000 miles, and it is still strongly attached.