if the ring was fitted incorectly it would break straight away. if it is a ring at fault i would say it is either ran lean on no4 and heated up piston and nipped a cowpression ring up which could be caused by been drove hard with either poor mixture or poor spark. Or possibly the engine may have been over reved and damaged at some point. how many miles was it when it started to play up. I assume it must have been at least over a 1000 miles as you first noticed it RACING down the by pass,which you wouldnt be doing for the first 1000 mile running in period. So this cancels out poorly fitted rings. Hope this helps and you get the trouble sorted ASAP.