DPF Delete Before & After: Real MPG, Horsepower & EGT Data for Ram, Ford & Duramax
Show Me the Data
"Better MPG" and "more power" are the two claims plastered on every DPF delete product page. But what are the actual numbers? We compiled dyno results, owner-reported fuel economy data, and EGT measurements from dozens of deleted trucks across all three platforms.
Here's what the data says — no manufacturer claims, just owner logs and dyno sheets.
Why the DPF Kills Performance
Before we look at gains, you need to understand what you're removing:
- Exhaust backpressure: A loaded DPF creates 3-5 psi of backpressure at the turbo outlet. The turbo must work harder to push exhaust through the filter, increasing drive pressure and reducing turbine efficiency.
- Regen cycles: Active regeneration injects raw diesel into the exhaust stroke to raise DPF temperature to 1,100°F+. This fuel is wasted — it contributes zero power and dilutes engine oil with unburned diesel.
- EGR recirculation: The EGR system routes hot, sooty exhaust back into the intake. This reduces combustion efficiency, increases intake air temperature (lower oxygen density), and accelerates carbon buildup on intake valves.
- Heat soak: The DPF acts as a giant heat reservoir under the cab. Post-regen surface temps exceed 600°F, radiating heat into the transmission tunnel and raising underhood temperatures.
Ram 6.7L Cummins: Before & After
| Metric | Stock (DPF Intact) | Deleted (4" Pipe + Tune) | Change |
|---|---|---|---|
| Peak HP (dyno, rear wheel) | 330-350 rwhp | 420-470 rwhp | +90-120 hp |
| Peak Torque | 700-750 lb-ft | 880-950 lb-ft | +180-200 lb-ft |
| MPG (highway, unloaded, 70 mph) | 16-18 mpg | 20-24 mpg | +4-6 mpg |
| MPG (towing 10k lbs) | 10-12 mpg | 13-15 mpg | +2-3 mpg |
| EGT (cruise, 70 mph) | 700-800°F | 500-600°F | -150 to -200°F |
| EGT (WOT pull) | 1,350-1,400°F | 1,100-1,200°F | -200 to -250°F |
| Turbo lag | Noticeable | Reduced ~30% | Improved spool |
Owner consensus: The 6.7L Cummins sees the most dramatic MPG improvement of the three platforms — partly because the Ram's factory DPF strategy is conservative with frequent regen cycles. A deleted and tuned Ram with our 4" delete pipe and a mild tow tune delivers better fuel economy while towing than a stock truck does empty.
Ford 6.7L Powerstroke: Before & After
| Metric | Stock | Deleted (4" Pipe + Tune) | Change |
|---|---|---|---|
| Peak HP (dyno, rear wheel) | 380-400 rwhp | 480-530 rwhp | +100-130 hp |
| Peak Torque | 850-900 lb-ft | 1,050-1,150 lb-ft | +200-250 lb-ft |
| MPG (highway, unloaded, 70 mph) | 17-19 mpg | 20-22 mpg | +2-3 mpg |
| MPG (towing 10k lbs) | 11-13 mpg | 13-15 mpg | +2 mpg |
| EGT (cruise, 70 mph) | 600-700°F | 450-550°F | -150°F |
| EGT (WOT pull) | 1,300-1,400°F | 1,050-1,150°F | -250°F |
| Turbo spool | Quick (VGT) | Near-instant | Minimal lag |
Owner consensus: The Powerstroke gains the most peak power — the 6.7L's Bosch CP4.2 pump has plenty of fuel headroom, and the factory VGT turbo responds well to tuning. MPG gains are more modest than the Ram because Ford's factory calibration is already relatively efficient. Our Powerstroke 4" delete pipe is the essential first step.
GM Duramax L5P: Before & After
| Metric | Stock | Deleted (4" Pipe + Tune) | Change |
|---|---|---|---|
| Peak HP (dyno, rear wheel) | 390-410 rwhp | 490-540 rwhp | +100-130 hp |
| Peak Torque | 880-910 lb-ft | 1,050-1,150 lb-ft | +170-240 lb-ft |
| MPG (highway, unloaded, 70 mph) | 18-20 mpg | 21-24 mpg | +3-4 mpg |
| MPG (towing 10k lbs) | 11-13 mpg | 13-16 mpg | +2-3 mpg |
| EGT (cruise, 70 mph) | 650-750°F | 500-600°F | -150°F |
| EGT (WOT pull) | 1,300-1,400°F | 1,100-1,200°F | -200°F |
| Turbo spool | Quick | Excellent | Wider powerband |
Owner consensus: The L5P is the most refined platform stock, and its factory efficiency is already good — so MPG gains are real but less dramatic than the Ram. However, the L5P's ECM is the hardest to unlock, which adds $500-800 to the total cost. The combination of our L5P 4" race pipe and 3.5" downpipe delivers the full potential.
Platform Summary: Which Deletes Best?
| Winner In... | Platform | Why |
|---|---|---|
| MPG Gain | Ram Cummins | Worst factory DPF strategy → biggest improvement when removed |
| Peak Power | Ford Powerstroke | CP4.2 pump headroom + VGT turbo response |
| EGT Reduction | Ford Powerstroke | 250°F drop at WOT, largest delta of all three |
| Easiest Tuning | Ram Cummins | EFI Live support is mature, CSP5 switching is reliable |
| Best Overall | L5P Duramax | Highest stock output, modest but real gains, excellent daily manners |
The MPG Payback Math
At current diesel prices (~$3.50/gal), here's when a delete kit pays for itself in fuel savings alone:
- Ram +4 mpg: 15,000 miles/year → saves ~$350/year → payback in 12-18 months
- Ford +2.5 mpg: 15,000 miles/year → saves ~$220/year → payback in 18-24 months
- GM +3 mpg: 15,000 miles/year → saves ~$260/year → payback in 18-24 months
Note: This is fuel savings only. Factor in eliminated DPF maintenance, regen fuel waste, and EGR-related repairs, and the true payback is faster.
FAQ
Are these numbers guaranteed?
No. Your results depend on: tune quality (custom vs canned), driving style, terrain, tire size, and truck condition. These are owner-reported averages from forum threads, dyno days, and fuel logs — not lab-controlled tests.
Will a delete pipe alone (no tune) give any gains?
No. The ECM will detect the missing DPF and trigger limp mode before you make it out of the driveway. The tune is not optional — it's required for the engine to run.
Does a 5" exhaust give more power than 4"?
On a stock-turbo truck with mild tuning: no measurable difference. A mandrel-bent 4" pipe flows more than enough for 500-600 rwhp. 5" becomes relevant above 650 rwhp or with compound turbo setups. Our 5" Ram exhaust is about future-proofing and sound, not peak power at moderate levels. See our full comparison.
Will my EGTs go too low after delete?
No. A deleted diesel at highway cruise will sit at 500-600°F — warm enough to boil off condensation and prevent wet-stacking. The danger zone for "too cold" is sustained operation below 300°F, which doesn't happen unless you're idling in sub-zero weather for hours.
Complete Your Delete
- Ram 6.7L 4" Delete Pipe — $219.99
- Ford Powerstroke 4" Delete Pipe — $199.99
- Duramax L5P 4" Race Pipe — $249.99
- L5P 3.5" Turbo Downpipe — $179.99
- Ram 5" Full Exhaust System — $629.99
- 5" Universal Diesel Muffler — $119.99
Related Articles
- DPF Delete Parts Checklist
- Backpressure & EGT: The Science
- 304 vs 409 Stainless: Material Guide
- What Tuner Do You Need After DPF Delete?
Legal Disclaimer: All performance data is for informational purposes from off-road test vehicles. DPF/CAT/EGR modification on road-going vehicles violates the Clean Air Act. Products are for off-road and competition use only.