I had long tube headers and off road x pipe put on and i have a sct x4 tuner. But after so many miles I get a lean code on bank 1 or 2 I forget I haven’t driven it much anymore because running lean is bad. So I found another shop that people said they specialize in mustangs the problem is since the epa is after people tuning cars for no cats they won’t touch it

another shop I found said they could but I’d have to get a hptuber. Is there a difference with hp and sct I know my x4 when I...

Tuning issues