One year ago I bought my NSX and had it smogged at a local gas station in Encinitas. When I walked in and stated my need, the smog guy asked "What kind of car is it?" I said "An Acura." He asked me for the keys, which I handed to him, and he walked out of the office. I watched him walk around the lot right past the car, looking back and forth all over the lot. Frustrated, he looked back at me and asked "Where?" I pointed "There, the red one!" He said "I thought that was a Ferrari." I said, "No, it's an NSX." (Nice start eh?!!!)
Once it was into the bay, two smog guys started to look it over. Neither guy knew where the engine was. Is it in the back? No! Is it in the front? No. Then where is it? In the middle!
They didn't know how to find the engine. They couldn't figure out how to open the engine lid. Once I opened it, they both stood there, one on each side of the car, looking down into the engine compartment like it was the plasma energy generator in an alien spacecraft from a different galaxy.
After this pause, they attacked..., leaning over, touching probing, feeling, reaching, and trying to find a place to ground thier smog tester. It took them about 20 minutes (not kidding) just to find a proper grounding site on the engine. Finally, they quickly did the testing and it was done: PASSED!
I strongly suspect that my experience is not unusual, because the NSX is so rare. So what is the probability that such gas station smog guys are going to figure out that you have some aftermaket mods? I predict ZERO, as long as you're not producing illegal levels of smog.
So I recommend that you go to your local smog guy at a gas station with little fear. Just don't do it at Acura.
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NSXY
95 NSX-T, 5 sp, Red/Tan, Stock, except Dunlaptya SP9000s