you weren't that specific.
for example you want "good" rof, well if your idea of "good" is "anything better than stock" then a basic mosfet and 11.1v battery will be all you need, if you want a 40rps hose then the requirements are going to be a bit more extreme.
you want 330 or 350fps, which is it? do you play more at sites with a lower limit that you'd rather go lower? do you want to be able to change with ease?
you want "good range", which can mean anything from just putting some geoffs .3's in a clean stock gun or dropping .48's into a gun with literally every internal part changed
this is the problem with providing recommendations as to whether for example putting a titan, which is an expensive and complex bit of kit that needs a lot of other factors in the gun to be up to scratch first, is the right thing to do or not.
this is why in lieu of anything specific the answer is to "leave it alone", if you have the impression the gun you're getting is going to be "good" (in your definition) out of the box then maybe you'll be sufficiently happy with the performance that you don't need to do anything bar keep it clean and feed it targets. likewise you might use it and find "hmm, i like the rof, and my bb's are going far enough, but the spread is terrible" or "hmm, my bb's are going where i want them to, but the trigger response is too slow" which can be as much down to personal preference and game style as anything else.