Sometimes I come across as a jerk- never my intent. But having been nicknamed sarcasmo by a couple people...
I cant really speak to cold start relations but I really think if it were that bad on a db pump the military would have abandoned the 6.2 before the 6.5 was ever made. So stock fueling starts ok for uncy sams ok.
So hopped up pump the issue? Problems to be overcome for the starting issues maybe a wabasto heater? Or running the baby soft injectors?
Now, the hopped up pumps for volume when combined with higher pop pressure injectors- there is a ratio of say 5:2 (5,000 psi pump and 2000 injector) on stock setups but if the pump builder doesn’t know how to rasie the output pressure along with the volume, then your pressure is going to fall- BECAUSE he doesn’t know how. New ratio-??? 4.4:2.3 maybe 4:2.3 who knows?
So now lower the pop pressure like he wants and you get back that ratio 4.250:17 is same as 5:2 It wont atomize as well but more volume gets through.
Maybe that ratio make atomization closer to stock?
When I wanted a pump “bumped up” it was a couple hundred. But my psycho pumps were a couple thou each, labor costs only. Starting with a new pump not included here. My point is like my thread about the cheapy wmi I am looking at- yeah it works, kinda but with issues. The right way is just way more money. Could be the issue?
Wanna pressure gauge on those pumps vs a new stock one yet?
So the builder was recommending way lower than stock pop pressures. So maybe Yes more fuel, but lessAtomization. Again think of wmi. What you want is volume AND pressure.
Yes in the harder starting cold areas, I would hesitate too until a pump builder could explain details of why the problems and show how it is solved. Maybe focus on return-ability of the pump if it cant handle the cold starts. Dont swap everything over until that is known.
Pump, lines, add a bicycle brake cable into the cab and some backyard bailing wire to the existing pedal just for testing and add it on the truck aduring know cold streaks. If all is good, then do the correct install. If it doesn’t work out and you get back all but a couple hundo, now you know. Sometimes gotta pay to play.
Or hit up heath for his merlin, just ensure return warranty if it doesn’t live up to the hype.
The two built pumps here are moose jr. At what was it 155cc? Remember they make a Bull moose at 200 cc.
You CAN NOT HIT 120 On ds4. 110? NOPE. Be the first Show me an uninterrupted video of one on a bench putting 105 through injectors and I will drop $40 for you congrats drink in an envelope to you for the new world record you set.
Want big power AND a ds4, ok. Just mount the Ford db2 on the other side of the timing cover and some
Lines going to the injectors feeding through the glowplug holes. Cummins air heater works nice for your intake with some tig welding. Why not 2 ds4? Because the pmd can’t handle 2 pumps, and you cant run twin pmds.
Tools for Db2 are not to different. There is a bar to use instead of prybar for fine pump adjustments, or make your own from 1” flat bar and 2 bolts. Replace your scanner with a paper clip and a diesel pulse adapter. Most people like the snapon that also has the eye that goes in the glowplug hole. I am content with my Mac ET18DPM in the picture that needs any inductive timing light hooked to it. Maybe buy the one of the hundreds of military type ones being auctioned off- I never used one of those, but shouldn’t be to bad.
Instructions very slightly based on tool, but mine is put clamp on injecton line, put ground wire on same injection line. Put timing light pickup (sparkplug wire clamp) on red metal loop. Power up timing light. Start engine and aim timing light at timing tab/ balancer mark just like old school gas engine.
View attachment 52028
View attachment 52029
IMPORTANT: turn engine off before adjusting pump. Lock down 1 of 3 nuts and start engine to recheck timing. Repeat 4-5 times when you learn how, then it is usually 2-3 engine starts after that now that you have a better feel for it.
All the info is here in this forum, including the how to convert manual. Invest some hours reading all the stickies and search the stuff you are missing.
But really you should dyno so you have an accurate reference. Do 0-60 time, maybe 1/4 mile. Then- what do you want it to be? Now the key- how much $
Did you balance the lower assembly of your optimizer? How many miles on the rubber band timing chain? Tons of questions- what heads are you running and how much work was done to them for flow? Guessing you are punched out huge if your thinking precup modification next?
Clearly I hit too hard with attempting to point out you don't have to put up with GM's screw ups for power on the 6.5TD because others don't. You are not wrong for the OEM setup, but, we have era specific larger OEM power numbers than a 12v Cummins. Sure others are easier to turn up, but, the gloves come off then and anything goes. This was an era before the HP wars and "Where is my MPG diesel economy?" 
