My biggest pet peeve is a double edged sword...I'm not mechanically inclined and I'll own that, I don't have the time to learn how to do it myself but I can afford to pay someone else to do it. I can do basic preventive maintenance but for major repairs I have to entrust it to an expert and those are hard to come by unless you're fortunate to live near one. Competent and (most importantly trust worthy/honest) TR mechanics are a dying breed. I realize that once you decide to take a 25+ year old car from 250HP to 600HP+ you're inviting problems, but I've now gone through 3 motors in 4 years with over $20K spent just for the motor. The first two were the fault of the builder and he took responsibility for the first but not the second, the third is yet to be determined but I'm not liking how things are unfolding and what has been discovered as it's being looked at now. And I don't beat on it, it's a weekend warrior show 'no go garage queen...I'm really frustrated with it and I hope this is the last time I have to have someone build me another motor.
The next would be the limited vendor pool for aftermarket parts, but when you drive a car that was built in limited numbers for limited years...you're stuck like chuck. I miss ATR, Kenne Bell, and Postons. But we're fortunate to still have vendors like Highway Stars, Mike McCoy, Full Throttle, RJC, Champion, GNS, Caspers, T/A, Old Buick Parts, and Kirbans.
The ASE and metric parts are annoying.
That other people lose their shit and forget how to drive when they pull up besides you because they're so excited by the car...it's annoying, but at the same time it's also rewarding when people react that way.
The window motors used to bother me until I put in a harness upgrade from Kirban's along with the faster window motors he used to sell (or may still sell).
The power antenna used to bother me, but Kirban's power antenna saver kit was some good insurance.
I guess I'm fortunate that I don't have wind noise or interior water leaks.