I’m just getting my S14 back on the road after a few years off & having done a lot of body work.
My tester friend says the new MOT is a lot stricter so it’s much better if you’re actually testing the correct car at the test these days. In years gone by I put the CAT back in anyway, but I can’t remember if that was when I was just running the stage 1 chip (actually I can’t quite remember if there was a stage 1 chip, I just remember I swapped it to a slightly updated version at some point). So I’m hoping it’s going to pass with the stage 1a chip & CAT in, and at the same time that the CAT isn’t going to get damaged.
I used to sometimes leave the CAT in for a little while before I had time to put the de-cat back & I have to say I didn’t notice a massive difference in performance. I’m only running a 2.5” exhaust & the standard CAT fits up to the 2.5” pipe perfectly.
So I’m just wondering if the AFR of the stage 1a chip is likely to damage the CAT if I left it in over a long time. I think richer mixtures can damage them.