The BCP Fuel Stumble Mod is a critical part of tuning your car safely and properly. We suggest this on all stage 1/2 cars and REQUIRE it on anything more.
Part number: BCP.GR.FRP
Regulator Type: Rising Rate
Lines/Clamps included: Yes
E85 capable: Yes
Tune is REQUIRED to use this product
Need a custom tune for your car? Check out our Dedicated E Tuning Website!
What is the stumble mod, and WHY do I need it?
The strange design of the factory fuel pressure regulator system causes an abrupt and obvious “stumble” or “hesitation” around 3,000-3,500 rpm at many different throttle positions on the 2008+ STI. This is mainly caused by resonance in the fuel lines and what we’ve found is that the resonance is exaggerated by larger injectors. If you are using larger injectors (like ID1050x or larger) you will feel this stumble even more. This issue is mechanical and cannot be tuned around without a stumble kit or other aftermarket regulator.
Our Stumble Fix Kit utilizes a different style Subaru OEM regulator and ethanol-rated injection hoses to offer a clean and effective solution to the problem. Keep in mind, tuning is required with this kit. As we noted above we have the best E Tuning in the business so follow the link above to order your tune!
If you are planning on doing any mods to your Subaru, consider these questions: How closely do I want my car to drive like stock? If you want your car to run smoothly after modifications, the BCP stumble mod should be on your list. The stumble is a well-known issue on the 2008+ STI and chances are, a friend has the BCP stumble mod on their car already. For the smoothest tuning experience, we suggest the BCP stumble mod and the Fuel Pressure Monitor kit combined together. If you have any questions, don’t hesitate to ask us!
Fuel pressure monitor can be found HERE