What other parts do you need for a big turbo on a Focus ST?

At the absolute minimum, you need:

• Intercooler piping with a blowoff valve

• Custom tuning

Things that make it very easy to setup include:

• Symposer delete with an air fitting - Provides a boost/vacuum reference for the new blowoff valve

• New gaskets, hardware - There is a lot of hardware you can reuse, but some of it should be replaced if it doesn't come with the kit you ordered or if you bought a used kit. Here are some links to common replacement items. There is some overlap here, this is not a list of hardware you need, only suggestions in case you do.
  
  • Oil Return Gasket
  • Coolant Line Banjo Bolt Gasket
  • Downpipe Inlet Gasket
  • Turbine Inlet Gasket (depending on turbo choice)
  • Oil Feed Line Filter
  • Oil Feed Line Complete Assembly
  • Turbine Mounting Stud (there are 4)

Things we suggest getting if you don't already have them:

• Oil catch can - Preferably both the PCV and CCV cans. A PCV one is important no matter what because the engine spends most of the time in vacuum, with the PCV (positive crankcase ventilation) valve open. With the new, increased crank case pressure being caused by the big increase in power, the CCV (crank case vent) one becomes more important than it did with a stock turbo.

• Upgraded intercooler - The stock one is not efficient with a stock turbo, let alone a bigger one.

A good idea to replace during install:

• Fresh oil

• One step colder spark plugs - If you already have some fresh ones, you're good.

• Fresh clutch - If your clutch is either stock, close to the end of its life, or both, a newer turbo is most likely going to make it reach the end quickly. But it is a separate install, so you don't really gain much by doing it at the same time, other than peace of mind.

Reasons why you need the bare minimum:

When you upgrade the turbo on the Focus ST, unless you are using the internally bypassed Garrett PowerMax or BorgWarner EFR turbos, you're most likely getting something that does not come with a blowoff valve built into it, like the stock turbo has. In the case of the Focus ST, an upgraded turbo removes the blowoff valve that existed before, causing the requirement for a new one.

The blowoff valve must sit between the throttle plate and the compressor wheel of the turbo and since it's usually not sufficient enough to keep the stock intercooler piping when you're upgrading your turbo, it's natural to put a blowoff valve in the new intercooler piping. This is why there are many intercooler piping kits on the market featuring blowoff valve flanges, even though the stock ones don't have it. It makes upgrading your turbo much easier.

In general, you need new intercooler piping, with either the cold side or hot side piping featuring a blowoff valve. We have both styles available. It's a no brainer to use one of the many symposer delete kits as the boost/vacuum reference for the blowoff valve to operate. The valve needs to see both so it can open and close properly.

As with any upgraded turbo, no matter the size, you need to tune the car. And we can help with that, too.