Dude, you’ll be fine, just as long as the basic safety stuff is ok, glass, brakes, suspension, headlights, signals, etc, they won’t even blink. 90 is old to them, you’ll have to pass the sniffer the first year, which will be cake, particularly with a brand new cat, then you’ll be exempt after that. Don’t sweat it, and don’t tell them anything, just go for a normal inspection.