Actually, the X-cellerator is so damned new, that realy isn't any hop ups out for it yet. if you checkl ebay you will find some out for the other newer XTM products out and about.
What I found out about the XTM, is that almost 100% of it is compatible withe other nitro rides.
You can get lunsford titanium turnbuckles for sure.
Losi XX-XXNt Wheels will fit for sure. there is one type for the front and one for the back
The Tires are the standard 2.2 (you can get any tire in 2.2) Mashers I do like, and paddles for snow
Shocks are pretty much standard, measure yours and see what they are, tell the LHS guy what you want. If he's too expensive, use the LHS guy to find out what you need, then go buy it online. I prefer to support my LHS if the owners are nice and easy to work with (who care about saving $2.00 when you can keep it local, and get good service)
As for roll cages, front bumpers, etc. Go to your LHS If they have stuff out where you can see it, grab that rc10t bumper, compare it to yours.. see if it fits, if not how much will it take? drill a hole or two.
If you can't see this stuff in the open, ask the LHS guy to pull it out form behind the counter so you can have a hands on
Just like anything it takes time for an aftermarket to get started, usually when it does, you can find anything you need.

Be patient. In A month or two you will be able to find anything.