>>>Can anyone categorically confirm or deny whether cat-back exhaust replacements such as the much vaunted Quicksilver invalidate US warranty?<<<
Your warranty will be just fine. Any damage that can be attributed to the exhaust won't be covered though. Suppose it cracked and fell off, damaging the diffuser. That would be your problem. Or if it leaked and the heat melted something, your problem. But the aftermarket exhaust may have some coverage. If you buy a Lotus Stage 2 and have it dealer installed you'd likely be covered though, but that is questionable. At the very least I think that any issues would be covered out of good will if nothing else.
Cat backs are fine to put on nearly any car. But there can be hassles and challenges from some car dealers with some aftermarket bits if something breaks and fix-it requests are made.
This should provide some interesting reading: http://www.sema.org/main/semaorghome.aspx?ID=8124
Your warranty will be just fine. Any damage that can be attributed to the exhaust won't be covered though. Suppose it cracked and fell off, damaging the diffuser. That would be your problem. Or if it leaked and the heat melted something, your problem. But the aftermarket exhaust may have some coverage. If you buy a Lotus Stage 2 and have it dealer installed you'd likely be covered though, but that is questionable. At the very least I think that any issues would be covered out of good will if nothing else.
Cat backs are fine to put on nearly any car. But there can be hassles and challenges from some car dealers with some aftermarket bits if something breaks and fix-it requests are made.
This should provide some interesting reading: http://www.sema.org/main/semaorghome.aspx?ID=8124