LS3. Straight pipe guttered Cats. 3" Catback. Mafless Tune. LTFT disabled. STFT Only (The tuner did this, I only understood what was happening after learning up on this stuff)
I noticed with my 3" rear mufflers (Free flowing), my fuel trims show a bit leaner. Around 5% mark. When I swapped out to factory (Ultra Silent) mufflers, my fuel trims drop down to 0% mark.
Is this some type of back pressure effect? And how could I get my fuel trims to drop back to 0% with the 3" mufflers without going to my tuner first?