Improving bass from a front ported speaker

Plugging the port usually reduces the bass output.

Move the speakers closer to the wall behind them. That should help. Plugging the port is not a good idea, IMO.

Agree. Plugging the port will skew the balance and literally make your speakers sound "congested," especially for male vocals, tenor sax, cello, etc.

Agree...plugging the port often results in a muffled presentation...have u tried a sub?

You want to improve bass, not increase output correct? Try it, you cannot hurt the speakers.

Did you setup the speakers properly in your room? I had the same problem with my new ushers, they had too much bass when I placed them in the same position as my older ushers that were back ported. I divided my room in 1/5's for my speakers and chair, used the cardas alignment for side wall distances and things popped into place. I also put more sub traps in my room on top of what I already had. Now the bass is perfect.
Some of The reviewers of these speakers plugged the ports but I really didn't want to do that.

The bass output has more to do with room and less with the speaker. Where they are, where you are, where the boundaries are all the important questions. I would start from scratch with speaker locations before anything else. My favorite is the Sumiko Master Set plan. Formulas did not work. Every room has its quirks. Trust your ears.

Speaking very generally, stuffing a port will raise the speaker's low-end rolloff frequency, but at the same time make it more gradual. There are also many gradations between completely open and completely plugged, depending on the density of material you stick in the port.

I'm with Brf . . . give it a try, you won't hurt anything. The side-effect of sounding "congested" is also highly dependent on the particular speaker and how loud you're playing them.

As far as materials go, maybe start with your sock drawer? Worked wonders for those ubiquitous Cerwin-Vegas I remember from my college days.

BEst way to get optimal bass is to experiment with different speaker positions, toe in/out, height above floor, listening position relative to speakers, etc.

In general, proximity to walls and especially corner will tend to increase bass levels, distance from same to decrease them.

Subtle changes in location/position/orientation can have a major impact. Aiming tweeters directly at listening spot can help tilt the tonal balance away from the bass.

Loosely/partially obstructing the port (yes, a loosely rolled up sock can work quite well) will generally reduce output in teh lowest octave, where boominess and resulting "one note" type bass is highly impacted.

All these things are easily reversable/changed as needed compared to more extreme options, like changing gear, so twiddle with all of these as much as possible and see what works best first before changing anything. Unconventional placements, like straddling corners rather than along a single wall, and orientations to help disperse the sound more evenly can often help.