My current payload capacity is around 1800lbs. I did not order the HDPP. What would I have to change to get closer to the numbers the HDPP offers? I have stock 18" wheels on my '18 SLT Screw 6.5' bed 4.4 with the tow package.
Would tires with an E load rating help? Would I have to add a leaf?

thank you!

 

You can do most of it but it isn't going to change the payload limit as given on the door sticker.

 

HDPP has a different frame tickness. Nothing you can do about it.

 

You can't increase your payload.

 

You most certainly can increase your payload. You can start by removing your tailgate, hood, back seat, and front passenger seat. If you live in a dry climate, you could get rid of all the glass.

 

Consider that, at 1800 lbs, you are already at ~75% of the payload of the equivalent HDPP version of your model (mine is about 2400 lbs for HDPP XLT 4X4 Screw 157"wb). You would have to spend a lot of money and time replacing perfectly good parts of your truck to get that last 600 lbs of payload. Even then, as stated above, your frame would not be as capable of dealing with the added stress of that 600 lbs. Are you able to reconsider how much weight you want to put in the truck? If you are towing, maybe move it to the trailer? Unless you just bought it, trading in your truck for a new HDPP model may be cheaper and quicker in the long run.

 

 

While I can't guarantee it, the front axle seems to be the same between HDPP and non-HDPP trucks; the Tasca parts listing only shows Raptor and non-Raptor versions, and the BBAS documents only indicate one axle (with a maximum capacity of 3750 pounds—p. 48/68 in the 2017 PDF).

The rear axle is shown as having a maximum rating at ground of 4800 pounds with HDPP (footnoted), so that doesn't seem to be as conclusive. The same table shows 8.80 and 9.75 versions of the the 3.31, 3.55 and 3.73 rear diffs, as well as the 9.75HD version of the 3.73 used in the HDPP, so that would strongly suggest a different rear axle. The parts fiche doesn't seem to list two different 9.75" 3.73 rears, but the one it does list is pricier than the other gear ratios, so I'd wonder if all 3.73-equipped 9.75 rear ends use the 9.75HD rear axle...but that's a guess.

I think the closest you're going to come to a definitive answer is pulling up the parts listings by VIN for both and HDPP truck and your turck and comparing them.

 

https://www.f150forum.com/f118/what-...nclude-407308/

https://www.f150forum.com/f82/hdpp-m...eption-395397/

 

Payload (What you can put into the truck) is about the only thing you can change.
This is adjusted by changing Curb Weight (How much your truck weighs empty.)
What is difficult to alter is GVWR. GVWR - Curb = payload.
GVWR Can be altered. You just need to find an up-fitter to do the engineering, install everything and re-certify your ratings (This is the expensive part as the up-fitter is assuming the liability for the engineering and certifying it to the DOT. )
It's Cheaper to buy a new truck in most instances...Many up-fitters won't even look at trucks below class 7 or 8 and much of their work is performed on trailers requiring specific ratings. Think oversized load trucks requiring permits and special vehicles to even be on the road.

These are examples of adjusting Curb Weight to increase payload. Removing the glass may be a bit extreme.
Other candidates for removal include
skid plates
rear bumper (depending on local laws)
Go on a diet....
Limit passengers
Smaller fuel tank. (Less fuel)
and of course leaving the kitchen sink in the kitchen is probably a good idea too.

These are great trucks with a lot of capability, but they do have limits.