Allroad 04; 2.7L bi-turbo- 6 spd, 140K - ABout a week ago CEL came on (not flashing) accompanied by faint smell of gas and no power over 60mph. VAG code was vague- citing emission system. Problem seemed to disappear. Today I was testing power by downshifting and giving gas- still fine- but that triggered the car sounding like it needs a new muffler. (vrooom...) I am off to the mechanic- wondering if it is catalytic converter or bi-turbos? I am original owner of car and it has had all dealer based services to date. Anybody have any similar experiences?