The Subaru WRX & STI is supplied with a small diameter crosspipe from the factory. The problem with this is that 50% of the exhaust gases need to travel through the crosspipe, and that can not be done fast enough with the OEM crosspipe in place. Do not worry though, the GrimmSpeed HiFlow Exhaust Manifold Crosspipe for the OEM header is the solution!
The GrimmSpeed HiFlow Crosspipe is made of 304 SS (all of it, the flanges, flex section and tubing) and has super thick, 14-gauge pipe-wall thickness, which is the most heavy-duty pipe you will find for this kind of application. Other pipes use cheaper, thiner steel and are marketed as "super light weight," not GrimmSpeed's. Their one-of-a-kind Triple Layer Flex Joint is not located in the bend, which increases the life expectancy of the flex section. This GrimmSpeed Header Crosspipe is built from 1.92" diameter 304 Stainless Steel tubing, maximizing exhaust flow from cylinders 2 and 4 to the manifold collector for faster turbo response and increasing performance by 10hp and 13tqs.
If you really want to maximize your performance gains, opt for the ceramic coated crosspipe which helps to keep the exhaust gases hotter and faster flowing!
- Boost transition is improved over stock
- Helps airflow in the mid to high rpm range