i know xrays are very popular and that the tc3 is very old compared to some cars out there. one of the top guys at our tack drove a tc3 for many years but now he has switched to a pro4 and he says its a little easier to drive.
but a tc3 still wins in major events, it all matters on who is driving the car. for a starter a tc3 is a great car. eray are much more difficult to work on and if you pratice enough you can get quite fast with a tc3.
however if you want to get competitive, you might want to look into getting a few hop ups. but what you get depends on the track. if your running indoor on carpet i would get a graphite conversion or if you wanna spend the big bucks, a BMI or IRS Chasis. in fact i am selling an IRS now on here take a look >>> TC3 Factory Team with IRS Carbon Chasis
by getting a graphite or bmi.irs carbon chasis it will stiffen the car up wich is great for carpet. out door a normal chasis is fine by by getting the graphite conversion it makes the car lighter as well a stiff but dont get a bmi/irs its no worth it, in fact is my make the car worse outdoor but it matters on your set up.
lastly setting up a tc3 correctly alone makes it much better and for that i would ask around your local track and see if you cant find another guy with a tc3 to help you set up yours.
i hope i helped you out a bit, Frank