I have an original catalyst from my R34 GTR it has "covered" around 30k and is in good condition as far as I can remember,(it's been stored in my garage for a few years as it hasn't been on the car) I also have my original ECU also off the car for quite some time,I'm not sure if this should stay with the car though for any future modding/mapping,maybe some of you guys could answer this before I potentially sell it !?