I am thinking about getting a couple of these and making my own component set...these are priced good and I like Mach5Audio.

How efficient are these speakers??? Will they get loud on 50 watts??

Depends on the application. If you're shoving them in a small sealed enclosure, they may need some more. I know mine are stressing in my doors with more than 35 watts, but they are also playing IB in essentially 2 cubic feet so there's virtually no air spring for cone control.

also are you going to make passive crossovers or run active, that'll make quite a difference

passive crossovers first...then I may move on to active

why are these mids rated at 100 watts rms if they are struggling with 35 watts?? Should that be no sweat for em??

Note the comment that they are in an IB (infinite baffle) configuration. That would be why. When running IB, thermal ratings are no longer relevant, and the driver is MUCH more efficient.

I'd really start out with active from the get go as it will really open up the tuning options.

Precisely. I'm running mine wide open at the moment anyways. Once I get some slope control, I'm sure they'll take more, BUT doubt they'll need it. Why would you want to throw 100 watts at something when it performs well at less than half?

doea any one have more info on mli65

what would be best box size? sealed or ported to what hrtz?

Well I have an Explorer and there are "pods" that I'm turning into small sealed enclosures

You should be able to throw some power at them. They'll let you know when they've had too much.

I'm throwing about 60 watts RMS a piece at mine, and with 2x 12db/octave HPF's, one at 80hz and another cut at 50hz, they need more power. They go loud enough, but I'm willing to be they could go a bit louder (and handle the extra power) with ease. IB in my doors.

Generically speaking in a car, it is a good recommendation to run IB for your mids unless you really know what you are doing.