I really think you should listen to veteran mech users on this one. I think that you are trying to play above your league at the moment. That doesn't mean you cannot get INTO that league, but you are going to have to do a little practicing, first. You need to learn Ohm's law, what type of voltage and battery to use, and most people using mechs are at least building their own coils first, not buying them. Seriously, why not use your new RTA on your current (regulated) mod first? Mechs require a great deal of knowledge, I would suggest hanging out in the mech mod forum for a while first, and also the coilbuilding forum, as anyone who wants to operate mech should know how to build their own coils and test them on an ohm's meter, etc. Sure you can buy prebought but even thinking that bumps you down the vaping ladder, IMO, as you are relying on someone else to do something you can do. Besides, coilbuilding is fun and a good skill to master. You probably need a coilbuilder's kit (with an ohms meter) some cotton and a few different types of wire. I'd go with kanthal first, it's easier. Get used to TESTING then using your coils on a regulated mod while you are learning Ohm's law, etc.
Please? No one wants to see you running into troubles here, really everything everyone is saying is simply to help.
Anna