They're saying if you don't plan on upgrading to a bigger turbo then don't spend the money on the charge pipe. The turbo outlet is where it's smallest, hence it's the restriction, not the piping. If you're going bigger turbo at some point then for sure make everything at least the same size as the turbo outlet which will be 2"
Easy drop-in Higher Flowing hot side charge air pipe for 2014 Focus ST 1.6L Turbo
Constructed in the U.S.A. from 100% 304 grade stainless steel with all mandrel bent elbows and TIG welding.
Deletes all “small” diameter sections between turbocharger outlet and the stock rubber intercooler inlet hose. Note: Please refer to the Fiesta ST Charge air system diagram in the tech page.
The stock turbo compressor outlet diameter is 1.5”. Most aftermarket turbo upgrades have a 2” compressor outlet diameter. Our pipe is perfect for big turbo upgrades down the road but can be used on your stock turbo with the supplied 1.5” to 2” silicone transition elbow.
This functional pipe has an additional 1” side port for a mechanical BOV (Tial, HKS, Greddy, etc.). That same port can be used to relocate the stock diverter valve onto this pipe when stock turbo is removed since the stock electric diverter valve is integrated into the stock turbo compressor housing.
Please note: If you don’t have plans to upgrade to a larger turbo down the road, we don’t recommend spending money on this part as it’s not necessary and there isn’t measureable gains to justify the cost. The choking point is really the turbo outlet itself at 1.5” OD and a bit over 1.25” inner diameter. You will be better served to put the money towards an intercooler upgrade as that greatly enhances the operation of the stock turbo.
If you use this part on the stock turbo now and plan to upgrade to a larger turbo later that sits in the stock location, all you need is a 2” to 2” 45 degree off the shelf silicone coupler and you’re ready to handle big turbo power up to 400WHP.