I put mine where the cat would be. only been in use for 10-11 months. Was verified as accurate when new on dyno. Had car on dyno for touch up the other day and gauge was out by 0.8 afr. Showing leaner than actual. In fairness I haven't calibrated it in about 5-6 months, laziness. I will re calibrate it soon and see if it improves. Other than that, no issues but once it did get stuck in heating mode, lucky I realised and shut it down and it was fine after a restart. I have a suspicion that if I didn't catch it in time it would've fried itself.