The advantage of an STI intercooler is made whole with a GrimmSpeed Y-pipe kit. Being able to sustain boost levels is the goal of every driver. But having to contend with disruption from stock components makes it difficult. The GrimmSpeed Y-pipe kit presents a high quality package that makes performance from the intercooler hassle-free. Everything you need is included so you do not have to search around for missing pieces. Each GrimmSpeed Y-pipe kit includes couplers, clamps, BPV turbo hose, and hardware. When it comes to Subaru STI exhaust setups, this can be an important addition.
You can use the Subaru y pipe kit with either a Grimmspeed or STI TMIC. The benefits to using this configuration are for both performance and endurance. The stock Subaru y pipe is not only restrictive, but lacks durability, as well. In certain conditions, it can wear down and fracture. Moreover, the Subaru y pipe is not tolerant of boost, especially under excessive heat. This can lead to problems like knocking and lagging. Eventually, it will need replacement. That is why many Impreza owners go the aftermarket route for a Subaru y pipe. Grimmspeed designed their kit using digital image rendering for flow simulation to prove its effectiveness. Of course, they also use higher grade materials.
Rather than being single casted, each intercooler y-pipe kit is a two-piece operation. This is to allow improved tolerance in relationship to the flanges. The couplers, tasked with ensuring the overall efficiency of the kit, are 5-ply silicone. Grimmspeed employs silicone due to its durability but perhaps as importantly, its smooth surfacing. Because of their silicone construction, the couplers in the intercooler y pipe kit ease airflow right through without it being constrained. Also included is a bypass recirculation hose. You will use this to sub out the previous factory hose so that the intercooler y pipe kit engages maximum efficiency.
It is recommended that you use the WRX y pipe set for the parts it is designed to mate with. Some drivers have attempted to install the kit with different aftermarket intercoolers, resulting in an improper fit and other issues. Grimmspeed created the kit for their TMIC and the STI part. Some slight modifications may be necessary for adequate fit with an STI intercooler.