Definetly not safe!!! Take your XCal-2 and Data-log the car. Enter in, coolant temp, intake air temp, MAF AD counts, RPM, spark, and load. Find yourself a good place to do a good 2nd. gear pull to around 5800 RPM, then shut it down. Don't forget to cancel your data-log, when you shut it down. Play back your data-log on live link, to see where everything is at. Another thing, you could dyno the car again on another dyno to see what you come out with there. It might be just a bad wide-band O2 sensor, at 4500 RPM your pulling pretty good on a dyno, your not at cruise speed to get a reading like 14.7, on your AFR. But to spike it like that, there's something definetly wrong with something. Data-log it first, to see what you come up with before you do anything drastic. After you data-log the car, post it, then we can all get a good look to give you a better idea, on what your next step should be. At 4500 RPM on a dyno pull, your AFR should be around 11.2 or somewhere in that neighborhood, Mike D. ( ITLRUN ) If you've never used an XCal-2 before, your going to have to get the vehicles strategy code. You can get that by plugging the XCal-2, into the ALDL port under the dash then scroll down til you see get vehicle strategy. It will be 7 digit, a combo of numbers and letters, just use the first 5 to configure your data-log. Let us know what you come up with, Mike.