Straight piped for power

Originally Posted by aszyd

They are insisting that you are losing low down torque due to the loss of back pressure from having no restrictions, such as cats, and a larger pipe diameter, which would increase flow. A tune would correct the A/F and bring some of that lost power back.

As for consequences, if you were really lean it could cause detonation and damage your engine. I doubt that's happening though. The ECU will compensate as much as it can.