[19bonestock88]

My car has been throwing an 0420 the past year or more due to a bad cat (it actually burned out its core or it disintegrated somehow) but running in closed loop and returning amazing mileage the whole time, it’s running in closed loop now with the header and a downpipe that doesn’t even pretend to have a catalyst. I plan to replace the sensors and add an extender to the downstream O2, unless my 0420 doesn’t come back (I cleared it after the exhaust install and it hasn’t come back yet)

I can’t tell much (if any) extra power at low RPMs, below 2k it feels about normal, just a touch louder/coarser. Above 3500 there is a small but noticeable gain in acceleration (most of that was just due to the header and not from the exhaust) and the sound gets intense and loud...

Bottom line- this thing RIPS!