as for the running, the changes might be slight so you wouldn't notice. had an 86 560 that ran well, but the exhaust didn't smell right. put it on the ignition scope and the firing didn't look right. put a set of wires on it and, voila', it straightened right out. customer never complained about a running problem, but was really suprised at the difference. a set of injectors will have the same effect. i love putting new injectors in kjet cars, they really wake up. good luck, chuck.