Subwoofer and VU meter project (need help) :/

[SnowyCheetah]

I'm doing a project replacing my subwoofers in my stereo system. The amp in the main unit has made the woofers smoke before, so I'd like to put some more capable woofers in. Currently are woofers rated at 100 watts, 6 ohms. I'd like to find 150s to put in, but I'm not sure if I should worry if any speakers I find are more or less than 6 ohms. I also would like to know if there is anything else special I should look for seeing as I am replacing subwoofers, not speakers that were meant for full-range or tweeter use.

The other thing I'd like to do is add VU meters to each speaker cabinet (2 cabinets, each with a woofer and tweeter) - one for each woofer and tweeter. Should I get straight-up meters and maybe use resistors to make sure their readings are correct, or would I be better off using rectifier-type meters? I am not opposed to adding battery/switch systems to each cabinet to power backlights for the meters.

Thanks, if anyone has ideas/suggestions/help! let me know if you need photos of anything, or additional info, I'll do my best to post it.