5lug brake caliper enhancement

My calipers were the original Aisin Advics 60-25 with a single brake piston.
Are there any calipers that fit without any changes on the original mounting points with double pistons?
These brakes are so spongy and undersized. Even a small improvement would be so nice...

 

I know this is old, but Might I interest you in trying some stainless braided lines?

I did it on my 07, it was a slight improvement, nothing major, but it at least made the sponge feeling much less. I think I saw someone theorize that with our older trucks the rubber lines get to the point where they dialate a bit more under pressure, so over time they give a bit more perceptible squish feel. Whether that's true or I just am operating under the placebo effect, it did stop me from worrying about it.

 

So I've been looking into what can fit under our 15" rim (going bigger there's more options) and I think I've found a 2 piston caliper that will fit after alittle bit of spacing. I plan to swap my rotors and pads first and then see if the 2 pistons make a difference.

Here is a couple of pictures from me mocking up