I run an Ash-Spec ECU & Have for over a year now. The Car performs flawlessly. It boost properly, has never detonated or harmed my engine in any way. I followed all the mandatory guidelines for the upgrade and everything else was tuned accordingly. The only noteable side effect was increased horsepower and rapid acceleration. I will put my stamp of approveal on anything Ash sells because he really knows the ZX. If you have problems w/ your Z after Installing this ECU I will guarantee that the problem lies in YOUR car, not the ECU from him