i have a problem with my escort rs turbo. When i put my foot down the car seems to be holding back when you hit four thousand revs and loud popping from the exhaust. if you eaze in the power in it seems to be much better but still not right.Please can someone help.

its running 1 bar.Drove the car home from cambridge friday not a problem. it only started doing it yesterday and today

its chipped. rev counter dosent drop to zero