The recommendation on our F-150 is to use a WDH if the tongue weight exceeds 500 lbs. So we are on the edge of that, as our tongue weight at the high end is around 570 lbs. We opted to go with the WDH, and we use the E2. We have plenty of tension on the WD bars, as we have to crank the tongue up quite a ways to get them to go on in the first place.

We also have a Tacoma, which has much lower ratings, and is a lighter vehicle as well. I am positive that we would use a WDH if we towed with it. No question.

So your issue is that you're putting something in the neighborhood of 400 lbs (give or take) on the receiver of your Tacoma. Given the moment arm, that is (for sure) reducing the weight on your steering wheels. Probably something on the order of 100 lbs, but I have not done the math.

I personally think that the mods you made on your suspension are leading you astray. With the lighter capacities of the Tacoma, I think you would be better off with a WDH. 

I would suggest that you go to this web site and plug in the numbers to see where you're at.

i have a fastway E2 600lb. trunnion wdh as well.  It works well.

Look at the pic from the instructions.  figure 2a and 2b. The top bolt that attaches the ball assembly to the receiver that goes in the vehicle has a slotted opening that should allow you to make the top of the ball assembly make contact to the rivet without much help from the bolt at the bottom.  Will yours not make contact if you do that?  I have 420lbs of tongue weight w/o water. Hope this makes sense....

I have a Reese Pro wdh. The issues I have with it are that it is quite time consuming to hook up because the sway control is done with two separate friction bars that have to be installed in addition to the trunnion bars, and that there is no room to adjust where the trunnion bar chain brackets attach to the A frame. 

The separately adjustable sway control bars are now starting to look like an advantage. The inability to change the A frame mounting points is still a problem for me though. Guess I'll do some more reasearch.

In my case even with the minimum WD setting (5 washers, L brackets in the lowest setting), it still over corrects, but the bars are so loose I can lift them off the L brackets by hand with only 10-15lbs of pressure.  That is not going to provide any noticeable sway control.

The other issue is that when I have the L brackets in the lowest holes the angle of the trunnion bars is enough different from the angle of the L bracket friction surface that it really just makes point contact between the two for absolutely minimum contact of the friction surfaces.

There is also the Tuson one that uses the brakes too but it uses them differentially where the Hayes applies both brakes.  The Tuson costs about double and is a way more complicated install because you have to tap into the individual brake wiring.  That seems more complex than it needs to be.

Oh well, it's not the first time I have wasted money, and I'm sure it won't be the last.

That is what I already did to begin with, and I even supplied them with all the measurements.  What they SHOULD do with this setup is swap it out for the 450/4000 since my beefed up Tacoma and this light 171 only has 380lbs MEASURED tongue weight.

I tell ya, I wish I had never heard of FastWay.

This is what I thought I would find.  Wrote to FastWay support, the ball is back in their court.  I also posted a review of this thing with my saga on the etrailer site where I bought it, but they won't publish it because it is a negative review.  That's why you only see 4 and 5 star reviews on their site.  

I was just looking at ours, and it either has 2 very thick washers, or 4 relatively thin washers. It's hard to tell, but it looks like there might be 4 thin ones, but that's not my main point.

I got out a short decimal measure, and measured the distance between the insert/drop-down bar and the inside face of the hitch head. I measured 0.8" in that space, and hopefully you can see it in the picture below. What does yours measure (irrespective of how many washers are in there)?