my escort rs cab had a scorpion pipe on it with a 4 inch tailpipe,i took it to ava and they told me it was holding the car back,it made 138 bhp atw, approx,i fitted a magnex which they still moaned about and that made 164 bhp atw,i made a couple of other small mods but the exhaust did reduce from about 2.5 inches to 2 inches as it went through the rear silencer.the 1 i have now isa like that.my pal has a mongoose and the noise inside the car is unbearable on long journeys,especially in the back.anybody else recommend the magnex?