luvtolisten;
The upgraded cap tweak is what I would do first.

twc644;
I have done the mortite tweak on several inexpensive speakers. It is especially effective on speakers that have a stamped metal basket. A horizontal brace in the middle and the auto sound deadening sheets (Fat Mat $45 for 25Sq Ft) really make a difference with respect to cabinet vibrations. Getting rid of cabinet vibration is a significant upgrade. Many high end speaker manufacturers use 2 and 3 inch thick front baffles to help fight vibration. A large part of the cost of Wilson Audio's speakers is tied up in the material they use to construct their cabinets. You don't want cabinets to vibrate!

That's one of the many reasons I love my ESL's, no cabinet and no crossovers. I do use electronic crossovers at 75Hz for my subs.

The great thing about these tweaks is they are cheap to implement. $10 will get you 90Ft. of Mortite rope caulk. When you apply it to the stamped basket just firmly press it down and cover the entire metal basket. You should end up with a 1/4 to 3/8 inch thick coating. If the coating is too thick it will change the cabinets internal volume. The harder you press the thinner the coating. When I do this I try to keep the thickness consistant. I have not tried this with speakers that have cast baskets. I don't see how it could hurt and it may help them also.
If you do this you might as well replace the stuffing with Polyfil pillow stuffing. It's another very small upgrade. It only costs a couple of bucks.
If your speakers have those spring loaded connectors get rid of them also. Proper binding posts are cheap. The horizontal brace is just a piece of wood (really cheap).

Several years ago my brother and I put together a modest system for our mother. The EPI's we got her were the first speakers I tried these tweaks on. She commented that the speakers sound smoother (her words) after the tweaks. I thought so too.

BTW I did the cap replacement on them also. Not Solen's or Jantzens but decent ones from Parts Express