I drove an X/1-9 once at NHIS in an SCCA race. It was an ITC car that belonged to my friend Russ. I built the roll cage for him and part of the payment was one race.
It was not fun. The car was too small for me and the engine was a dog. I thought it belonged in ITD (non-existent class).
I liked driving his A Sedan Camaro a little better when I took my first driver's school, except that I hit (tapped) a Jersey barrier when I lost the rear end braking for turn 3 on a wet track.
I also drove the camaro to the track and home to CT because his tow vehicle (S10 with a 350) was running lean and couldn't handle the load. I was nauseous when we got to New Hampshire, and since the muffler fell off while I was on track I couldn't hear when I got home. I also got stopped by a Mass State Trooper and got a warning for a Too-loud muffler, lol.
Russ also ran an X/1-9 that I sponsored in an enduro at Riverside Speedway a couple of times. I still have the trunk lid with my logo on it hanging on the wall at my shop.
Here's a pic of an X/1-9 that I sometimes compete against in FP. It's owned by Giovanni Tartaglia.