wondering if anyone could help me. my el falcon has had a modified exhaust put on it. and has run well or the last six months and all of suddon it doesnt have as much power it is definetly not in limp home mode. and the exhaust is not as loud any more. i have driven it like this for about 2 months now and about a week ago i shook the exhaust because i thought it had come loose but it hadent but then it had its power back all of a suddon and it was louder again and has been fine for a week but today it happened again loss o power and quiter exhaust.

it also clunks from first to second gear which i believe is the s5 soliniod. would that have anything to do with it?
thanks fergus

Yeah i agree sounds like the catalytic converter is shagged.

thanks guys any idea what a cat costs to replace .