How hard is it to change throttle bodies, pls help

[tireburner163]

First, to answer your question, it's a walk in the park, a short walk in the park. A easy mod.

Now secondly I'm going to advise you to not get a 70mm TB at this point. The next mods I would do would be gears, you'll feel a HUGE difference there, and a off-road H-pipe. Both of these mods will give you much more power than a bigger TB. A TB just isn't going to add all that much power at this stage in your mods.