ExactlyHere's my problem with this question.... And I've certainly pondered it (selling and going c6z) too. My TA build has been going on for 5+ years.
Fact of the matter is, i know DAMN well that if i got something else, it's only a matter of time until i start modding that car too. Sad part is, I'd be back into payments AND back into mod "payments" to make the next car keep up with what I've got now in the TA.
I'm guessing you're in a similar place.
Question comes down to this IMO: are you done with modding? Or are you just bored of the current car and want to start over? I think most of the true car people here understand that a new car = starting over. Because i know for sure that I'd only be happy for so long before i start tweaking and wanting more from the next car. "More" that my current car already offers.