Diesel Lion Delete Kit Reviews: What Buyers Need to Know Before They Commit

Diesel Lion's lineup is built around three named tiers, each targeting a different buyer. Stage 1, called the "Cub," bundles a basic EZ Lynk tuner with EGR Delete (Exhaust Gas Recirculation) and DPF Delete (Diesel Particulate Filter) hardware. It's positioned as the entry point for a full delete without any exhaust upgrade included.

Stage 2, the "Young Lion," adds a 4" stainless exhaust, a throttle valve delete, and TCM (Transmission Control Module) tuning aimed at the 68RFE automatic. That TCM tune matters — the 68RFE is known for shift quality degradation under added torque without supporting calibration.

Stage 3 is marketed as the ultimate package, though specific component differences from Stage 2 aren't clearly documented outside their own product page .

Their tunes are delivered via EZ Lynk's cloud-based platform. That architecture means your tune files live on a remote server and push to the truck over a wireless connection — which works fine when it works, but introduces a dependency on both hardware connectivity and ongoing server availability that a pre-loaded handheld device doesn't share.

Here's the thing — when you're spending $1,400 or more on a delete bundle, the vendor's own product page isn't a substitute for independent validation. A healthy delete kit ecosystem produces owner forum threads, YouTube install walkthroughs, and owner posts with before/after fuel economy logs.

For Diesel Lion, that paper trail is thin. Their feedback page includes limited customer responses. The most detailed testimonial comes from an EcoDiesel owner who mentions ECM and transmission tune satisfaction — but the 3.0L EcoDiesel is an entirely different platform from the 6.7L Cummins. One owner's positive EcoDiesel experience doesn't validate how the kit performs on a 6.7L Cummins running an 800 lb-ft stock tune baseline.

This isn't necessarily an indictment — newer vendors build review volume over time. But before you commit $1,449 to any kit, you want more than self-published feedback. Search for "Diesel Lion Cummins" on diesel owner forums or diesel-specific Facebook groups. If threads don't surface, that's a data point worth weighing.

Let's talk real numbers. The 6.7L Cummins — producing 400–420 hp and 1,000–1,075 lb-ft in factory form depending on model year^[1] — loses a meaningful amount of efficiency to emissions system overhead. The DPF requires active regeneration cycles^[3] that dump raw fuel into the exhaust stream and raise Exhaust Gas Temperature (EGT). The EGR routes hot, soot-laden exhaust gas back into the intake^[2], reducing combustion efficiency and accelerating intake fouling.

Removing both systems and tuning for the new airflow path eliminates those losses. Across the broader diesel performance community, full deletes on 6.7L Cummins trucks consistently produce fuel economy improvements in the 1.5–3 MPG range for mixed driving^[4] — highway gains trend higher, city lower. Power gains depend heavily on the tune: a conservative economy tune might add 20–30 hp; an aggressive power tune can push significantly higher.

What Diesel Lion's site doesn't provide is model-year-specific dyno data or MPG logs from actual owners . General delete benefits are real and well-documented across the diesel community — but specific claims for a specific kit need specific evidence behind them.

Before you pick a kit — from any vendor — run it through this checklist:

1. Tuner platform stability: Does the tuner connect via OBD-II or bench flash? Cloud-dependent platforms introduce connectivity variables. Pre-loaded or locally stored tune files eliminate that dependency.
2. Tune file specificity: Are tunes written for your exact engine family, year, and horsepower level? A tune built for a 2013 6.7L Cummins will not perform the same on a 2019. Year-specific calibration matters.
3. Exhaust pipe diameter: A 4" pipe is minimum for a deleted 6.7L Cummins. A 5" pipe significantly reduces backpressure at higher power levels and is the preferred spec for any truck making over 500 hp at the crank.
4. EGR delete hardware fitment: Cheap EGR block-off plates and cooler bypass kits develop boost leaks. Look for billet aluminum or stainless hardware with proper gasket surfaces.
5. Post-sale support structure: Lifetime tune support means different things at different shops. Understand whether you're getting a ticket queue or direct tech access before you buy.

Any kit that doesn't clearly address all five of these — including Diesel Lion's — deserves hard follow-up questions before you hand over your card.

EZ Lynk hardware is used across the delete kit market, including by Diesel Lion. The platform connects via OBD-II and communicates with a smartphone app to download tune files from a calibrator's cloud account. That workflow has real advantages — remote tune updates without shipping a device — but it also means your tuner needs an active account and working server infrastructure to push revisions.

The diesel community's experience with EZ Lynk systems has been mixed, and the variation isn't usually the hardware — it's the tune files and the calibrator behind them . A well-written tune on EZ Lynk hardware runs clean. A generic or poorly calibrated tune causes issues regardless of the delivery platform: unresolved Diagnostic Trouble Codes (DTCs), rough shifting on the 68RFE, or EGT spikes under load.

For 2019–2021 Ram Cummins owners specifically, the 68RFE TCM tune is non-negotiable if you're adding power. The transmission's shift pressure tables are calibrated conservatively from the factory. Add 100+ lb-ft without updating the TCM and you accelerate clutch pack wear. Any kit that advertises power gains for this platform without mentioning TCM calibration is leaving something out.

Use this framework when comparing any delete kit, including Diesel Lion's tiers:

The pattern is consistent across the market: entry-level kits omit the exhaust and TCM calibration — exactly the two components that determine whether your 68RFE survives the added torque load and whether backpressure improvements actually translate to seat-of-the-pants performance. Factor those add-ons into your total cost comparison before any sticker price impresses you.

Here's the thing — most delete installs go smoothly. Remove the DPF, pull the EGR cooler, install the delete pipe, flash the tune. Done. But some don't. A delete tune that doesn't fully suppress SCR (Selective Catalytic Reduction) codes will throw persistent DTCs. A throttle valve delete that isn't addressed in the tune file will create vacuum anomalies the ECM doesn't know how to handle. A 68RFE that isn't TCM-tuned will shift hard under boost and eventually kill the clutch pack.

When those scenarios happen — and they do — you need someone answering the phone or the message queue who knows 6.7L Cummins calibration at a technical level. Not a generic support ticket routed to someone reading off a FAQ. A technician who can pull your tune file, identify the miscalibration, and push a revision remotely.

The diesel owner community has documented what happens when that support isn't there: owners stuck with codes they can't clear, tuners that can't reconnect after a battery event, and vendors who stop responding after the sale closes. Lifetime support isn't a marketing phrase — it's the actual safety net for a modification that touches your ECM, TCM, and emissions architecture simultaneously.

We've done the hard work of matching every component to your specific model year and engine. The Ram Cummins 6.7 Full Delete Bundle for 2019–2021 — one of our most popular Cummins packages — bundles a tuner, full EGR delete hardware, and your choice of 4" or 5" exhaust system, all calibrated for the fourth-gen Ram's specific fuel system and emissions architecture.

For 2013–2018 owners, the Ram Cummins 6.7 Full Delete Bundle for 2013–2018 covers the third-gen platform with the same approach: year-specific tune files, full physical delete hardware, and lifetime support from our technical staff.

We're not going to claim dyno numbers we can't put a methodology behind. What we will tell you is that every bundle we ship has been run through real-world testing, the tune files are calibrated for each year range, and our support team picks up the phone. The diesel community rewards transparency — and that's how we've built our reputation.

Disclosure: The Diesel Dudes sells the products mentioned in this section. Our recommendations are based on hands-on testing and customer feedback.