I'm going to order some Hi Flow Cats this weekend and leaning towards Seans.
I have 6.5 Roe, Vec3, 1.7 HS's, 1 5/8" B & B 's w/3" catless out the back now.
Will adding hi-flows require any change in tune?
Also,
I've had the rear O2's zip-tied up out of the way for 6 yrs now (no codes...