True, but I can easily tell the difference after I noticed the awful oil burning smell and blue smoke chugging out of my exhaust for almost a year.

Before I saw blue smoke from oil burning, I did see white smoke from my car and it was pretty easy to tell but some people probably won't know. It is very easy to tell if you pay attention to the smell though.

 

If the cat material disintigrates, it can get sucked into the exhaust ports and pulled into the engine. It will very quickly eat your motor. This effect allows us to get by without EGR valves.

I don't think this is nissan/infiniti's fault. Bad aftermarket cat (or bad tuning leading to bad aftermarket cat) = damaged engine.

 

That's why HFCs have an off road use only disclaimer when you buy them. Technically they're not legal and guess what OP...

You illegally modified your catalytic converters and now have a damaged motor as a result. That's exactly what the court would say if you tried to sue Nissan/Infinti for your car's problem right now.

I say get your motor looked at and go from there. Maybe the problem isn't as bad as you think

 

To the OP, what year is your G? How many miles were on the Crawfords? I have Crawfords on my G and I'm thinking about changing them for Berks. Berks have a metallic substrate instead of ceramic.