I started out with a 01 gmc sierra. ppe stage 5 trans, fass system, 30% injectors, ppe manifolds am up pipes, intake heater delete, intake,exhaust and efi by dmaxtuner. Well i started loosing rail psi. Culprate was stock cp3. So i i decided to go all out on the build. Dual stock pumps(ppe kit) and twins (s475 over stock), and a dmax tuner tcm. The truck has 4-5k rail psi at idle an instantly ramps up to 25k+ when i start driving. But it has absolutely no power only builds 5-10 psi and all you can do to see 45 mph.And no smoke at all even reving(didnt smoke much before, but like stock now) on the snap on scan tool everything looks perfect. Would the ecm not being tuned for the twins an dual stock pumps be why its acting this way?

 

the dual pumps wont matter, whatever rail press is tuned will be split to both cp3s by the ppe electronics. Setting any codes? Do you have any boost leaks? Are you using any kind of boost fooler on your stock turbo waste gate? I would deff. call dmaxtuner and have them re write you a tune for your new add ons. You can add a whole lot more fueling into your tuning now and will want them to re map your injection timing.