Recently decat my cefiro a33 2.0, used back original diameter which is 2inch, 1 silencer in the middle and 1 mufler(1in 2 out) at the back, and 2 exhaust tips behind. After decat, FC improved alot, low end torque improved(just need to tap the accelerator a bit to move the car compared to last time), high end torque almost the same. Im quite satisfied with the setup only the thing that sucks is, when i release the exhaust, the RPM drops instantly and the 1 in 2 out exhaust which has 2 slow...