What are your thoughts on Overstocking Larger Cichlids? I really don't recommend it personally but it can be done with some success. Now I am not telling you go out and buy a bunch of juvi Cichlids that are going to get 10in plus and fill your tanks. That is not what the thread is all about.
I personally have a CA/SA Cichlid tank which most as well as myself consider to be overstocked.
Here is the stock:

1x 10+inch Jack Dempsey
1x 6 inch Female Jack Dempsey (pretty much full grown
1x 8 inch Oscar give or take
2x Severums 8inches give or take
1x 4 inch firemouth
4x HRP's

Filtration is Rena xp3
2x Emperor 400's
Large Powerhead with sponge
50% weekly W/C

The tank is non aggressive to say the least...I think the smaller Cichlids balance out the aggression. The mix works for me although it took some tweaking and moving of fish to achieve this. Now you say it is overstocked.....I never let nitrates get over 40 ppm...and the fish pretty much keep to themselves with the occasional chase out of ones territory. No damage is ever done.

What are your opinions on overstocking Large Cichlids and your opinions on my stock?

First, what size tank, LOL? Second, how long have ya been keeping the fish in this set-up with the current filtration and waterchange regimen?

Nitrate toxicity is dependent on species and size. Larger fish are more tolerant of higher amounts. Unlike ammonia and nitrites, nitrates are seldom lethal immediately; they result in long term health effects. In addition, fish will adapt to high nitrates over time. If ya put new fish in a tank that has seldom had water changes over a period of time, the condition of the newcomers will deteriorate rapidly even though the old inhabitants survive. I don't have any info on cichlids, as there are none in the creek we discharge our wastewater into, but most salmonids are susceptible to nitrate poisoning at 10 ppm regardless of size (species factor). That (partially) sets our discharge parameters. I've investigated the literature and found claims that anything from 20-25 ppm up to 50 ppm is acceptable for freshwater fish long term. Again, it varies. Species in waters with high biodegradation may regularly encounter 200 ppm. Personally, I like to keep it 20-30 ppm or lower.

In the past, I have regularly exceeded the suggested stocking limits that I've come across since I started looking at forums. Not grotesquely, but enough so that I'm sure I'll face some condescension when my tanks are up and running and stocked a few months down the road. I've already encountered that condescension when making a point about stocking as it is. I can't believe how conservative the suggestions are at times. More than anything else, water quality and aggression dictate to me what fish go in a tank, along with the fact that I'm severely anal about maintaining biotope tanks. No mixing species from different continents here, LOL. As unscientific as it may sound, at times I'll stock based on "feel". If it doesn't "feel" right, I don't do it. That personal factor aside, I see no harm in, and have never experienced problems from, mild overstocking as long as the fish are not fighting, are healthy, and the filtration/water change schedules are adequate to maintain good water parameters.

WYite

The tank is a well established 125g. I always keep Nitrates under 40ppm usually under 20-30ppm just depends if I go 7 or 10 days between water changes! The fish have been together a few weeks but have grown up together in other tanks sense I have had them. It is working out for me and most of the fish are adults now. Just thought I would share.

I have done this a few times. Tank was like a 300 and it was a cichlid community that worked well.
I had kept:
sevs
oscars
geos
uarus
Jags
Reddevils
etc

As I have said before somewhere else on here...overstocked is a relative term. If you can maintain nitrates at or below 20 ppm (IMO) through your water change frequency and amounts then your tank is not overstocked. You may need to increase frequency and amounts for water changes when the fish get larger.

The other reason to not overstock cichlids is to keep aggression down in the tank. If there are no aggression issues in the tank I would say you are set. However it may become an issue in the future as I have found tank dynamics may change over time.

Oh and it looks like you have enough filtration present for that tank.