MMX Frequently Asked Questions / Xtreme Answers

Straight answers from the MMX shop — drawn from real customer questions and the same topics that dominate Gen3 HEMI forums and Facebook groups every week. For deeper writeups, see our HEMI Tech Section.

How do I know if my vehicle has VVT (Variable Valve Timing) or not?

Non-VVT: 2003–2008 5.7L HEMIs and all 6.1L SRT engines (roughly 2005–2010).
VVT: 2009–newer 5.7L “Eagle” engines, 6.4L / 392, Hellcat 6.2L, and most later truck/SUV applications.
When ordering cams, MDS kits, oil pumps, or timing parts, always confirm year, engine size, and car vs. truck — fitment is not always interchangeable.

What kind of tuner works with my vehicle?

Both Diablosport and HP Tuners have the capability to tune most Gen3 HEMI vehicles. When selecting a handheld tuner it is important to know which tuning format your tuner uses (Diablo or HP) and select your handheld accordingly.

Can I use a stock Intake Manifold with your Ported Throttle Body?

Yes, you can use the ported throttle body with a stock intake and you can use a stock throttle body with a ported intake.

Will I have to get my vehicle tuned to do an MDS Delete?

Yes. While you will not always need a full custom race tune just to disable MDS, you do need a handheld (or remote) tuner so the PCM stops commanding MDS. Without that, the PCM can still cut fuel/spark when it thinks it is in 4-cylinder mode — even if the hardware is deleted.

Does the Hellcat Supercharger Adapter kit come with the supercharger?

No, the adapter kit is only to adapt the Hellcat blower to a non-Hellcat vehicle. The kits do not fit any truck; they are for cars only.

Does your Drop in piston and rod package include bearings and gaskets?

We do offer the bearings and gaskets as an option in the drop-in piston and rod packages — just select the appropriate option prior to adding it to your cart.

I experienced a lifter failure, will I need to replace my whole engine?

In most cases, if you have caught the issue early enough an engine replacement is not necessary. But it is always recommended to have an experienced shop check your engine for damage to be sure. If you already have a hard P0300 / misfire tick and metal in the oil, stop driving and inspect cam lobes and oil for debris before deciding between a valvetrain repair and a full rebuild.

Will I see horsepower gain if I change my injectors?

If all you are changing is your injectors, then no — you will not see any HP gains. Larger injectors support fuel demand for cams, boost, nitrous, or higher power goals; the tune and airflow make the power.

How much horsepower will I gain from this?

Horsepower gains are always approximated, and generally depend entirely on the tune and other modifications on your vehicle. It is very hard to answer that question with a single honest number for every car.

Do you guys offer any sort of Dealer Pricing?

YES! We offer Dealer pricing on all of our products except for items marked as on sale. If you are interested in becoming a dealer with us, follow this link https://www.modernmusclextreme.com/t-mmx-dealers.aspx and complete our dealer application. Once all of the necessary documentation has been received and you have created your account online we will apply your dealer discount to your account and you will be able to purchase directly through our website and receive your dealer discount.

How long does it take for you to ship my order once it has been placed online?

Although we always try to ship the same day, most orders will ship within 24–48 hours of the order being placed. If you have special instructions about your order after shipping, please give us a call and we will try our best to accommodate.

Do you offer tuning as a standalone service?

We do offer remote tuning for a selection of our camshafts, but we do not offer tuning as a standalone service yet.

Does your throttle body include gaskets and bolts?

No — the ported throttle bodies are a direct bolt-on and you reuse your existing gaskets and hardware. The exception for this is the Hellcat Throttle Body Adapter Kits and the HEMI 80mm Throttle Body Adapter Kits.

Community & Tech FAQs (Gen3 HEMI Forums & Groups)

These are the questions we see most often on ChallengerTalk, LX/Charger forums, Ram forums, and HEMI Facebook groups — answered the MMX way.

What is the “HEMI tick,” and is it always MDS?

The classic tick is usually a failed roller axle / needle bearing in a hydraulic roller lifter. The roller stops spinning, skids on the cam lobe, and can grind metal through the engine.
Early warning: light tick at idle. Later: misfire, P0300, and metal in the oil. If P0300 shows up with a tick, stop driving and inspect — chasing coils/injectors first is a common (and expensive) dead end.
MDS-equipped engines get a lot of attention online, but valvetrain damage is not limited to “MDS only” cars. Read our full writeup: HEMI Lifter Failure, Tick & P0300.

MDS disable vs. full MDS delete — what’s the difference?

Tune-only disable (MDS off): A handheld/remote tune turns MDS off in the PCM. No hardware change. Easy, reversible, and popular for daily drivers who want fewer 4-cylinder transitions. Stock MDS lifters and cam stay in the engine.
Full mechanical MDS delete: Non-MDS (Hellcat-style) lifters, MDS block-off plugs, typically a non-MDS cam, and PCM calibration so MDS is never commanded. This is the approach we recommend when you are already in the engine for a tick repair, cam upgrade, or prevention build.
Forum shorthand often says “MDS delete” for either one — confirm whether people mean software only or hardware + tune.

Can I just unplug / plug the MDS solenoids and leave the stock lifters?

Plugging solenoids or deleting them without non-MDS lifters + plugs + tune is incomplete and can create oiling or driveability problems.
For a real hardware delete: install quality non-MDS lifters (we use the larger-bearing Hellcat design), install MDS plugs so pressurized oil can lubricate the lifter bodies/rollers, run a compatible non-MDS cam when required by the kit, and tune the PCM.
Shop kits: MMX MDS Delete / Repair Kits.

Will an MDS delete fix my existing tick?

Only if you also replace the damaged parts. A failed lifter often flattens the cam lobe; new lifters on a ruined cam will not last.
Best practice when the engine is open: new non-MDS cam + full set of non-MDS lifters + MDS plugs + gaskets/timing parts as needed + tune. If there is metal throughout the oil system, budget for cleaning, filter/oil changes, and possible bearing inspection.

Do I need a Hellcat oil pump with my cam / MDS delete?

A Hellcat (high-volume) oil pump is a popular add-on on forum builds and is available as an option on many MMX kits. It is not a magic “tick cure” by itself — correct lifters, plugs, clean oiling, and install quality matter more.
Match the pump to your engine family (VVT vs non-VVT, car vs truck) when ordering. If you are unsure, call us with year/make/model/engine before you click checkout.

Do I need a custom tune for a ported throttle body, cold air intake, or headers?

Mild bolt-ons can run, but a proper tune unlocks idle quality, throttle response, and real power — especially once you stack parts.
Camshafts, MDS hardware deletes, larger injectors, forced induction, and nitrous should not be run without appropriate calibration.
DiabloSport and HP Tuners are the two platforms most HEMI owners discuss; pick one ecosystem and stick with it so handhelds, credits, and tuners stay compatible.

Eagle vs. Apache vs. early 5.7 heads — why does everyone argue about this?

Early 5.7 (pre-2009): Different heads/intake packaging than later Eagle engines.
Eagle (2009+ 5.7): Improved ports/chambers vs early 5.7; common on cars and trucks.
Apache (6.4 / 392): Larger ports; often the head of choice for high-RPM or big airflow builds. Chamber size and compression change when you swap head families — plan pistons/gaskets/tune accordingly.
Intake manifolds and throttle bodies are not “one size fits all” across head generations. When shopping intakes/TBs, use year + engine size + car/truck application, or ask MMX tech.

What size throttle body do I need (80mm / 87mm / 92mm / Hellcat)?

Stock NA HEMIs commonly use an 80mm style TB on many 5.7/6.1 applications; 6.4 and Hellcat platforms step up in size (factory 6.4 / Hellcat hardware is larger).
CNC ported units and adapter kits change what bolts up — adapters (Hellcat TB to non-Hellcat intake, HEMI TB to Pentastar, etc.) are not the same as a drop-in ported stock-style TB.
Always match TB to intake flange and vehicle electronics; some swaps need a throttle position relearn and/or tune.

After a cam and lifter install, do I need a special “flat-tappet” break-in?

Gen3 HEMIs use hydraulic roller lifters — not old-school flat tappets. You do not need the classic high-RPM flat-tappet cam break-in ritual.
Still critical: pre-lube / prime oil pressure before first fire when possible, correct cam bolt/pin torque, clean assembly, correct oil level, and verify oil pressure immediately at startup. See our cam pin and break-in tech: Camshaft Pin Tech and Stroker Break-In.
Many builders change oil after initial run-in miles to catch assembly debris.

What oil should I run to help prevent HEMI tick?

There is no magic bottle that replaces good hardware and maintenance. Use a quality full synthetic that meets your owner’s manual viscosity (often 5W-20 or 0W-40 depending on application — check your specific vehicle), keep oil changes on time (many performance owners go shorter intervals), and avoid chronically low oil level.
If you already have a tick or P0300, oil additives will not repair a failed roller — inspect the valvetrain.

Will deleting MDS destroy my fuel economy?

MDS exists to save fuel in light-load cruising. Turning it off (tune) or deleting it (hardware) typically costs some MPG on the highway, but many owners report the difference is modest and prefer full-time 8-cylinder operation and the reliability strategy of a proper delete when the engine is already open.
Driving style, gears, tires, and tune affect MPG more than most forum arguments admit.

Can I run non-MDS lifters on a stock cam (or stock lifters on a non-MDS cam)?

Non-MDS lifters on a stock MDS cam is discussed often; it can work with MDS disabled in the tune, but lobe design and oiling strategy still matter — follow the kit instructions for your exact combination.
MDS lifters on a non-MDS performance cam is the wrong direction for a delete/performance repair.
When in doubt, buy a matched MMX kit so cam, lifters, plugs, and supporting gaskets are specified together.

Do forged drop-in pistons mean I don’t need machine work?

“Drop-in” means the package is designed around stock block bore sizes and common deck heights for the listed applications — not that every worn engine is ready without measuring.
Always check bore condition, ring gap, bearing clearances, and rod length. Download: MMX Drop-In Piston & Rod Install PDF.
Stock 5.7 cranks and rotating assemblies have power limits; forced induction / heavy nitrous usually wants forged pistons/rods (and sometimes more).

I’m doing a HEMI swap into a classic Mopar / resto-mod. What do I actually need?

Beyond the engine: mounts, oil pan clearance, exhaust, cooling, fuel system pressure/volume, drive-by-wire or aftermarket ECU strategy, and transmission compatibility.
MMX carries conversion-oriented parts (mounts, pans, intakes, fuel, engine management accessories). Start with our Resto Mods & HEMI Conversions category and the Joseph Hinds / Larry Shepard books in the Tech Section.

Should I lock out VVT or leave it active with a performance cam?

It depends on the cam design and the tune. Many street cams are designed to work with VVT for a broader torque curve; locking out VVT without a cam/tune package that expects it can leave power on the table.
Phaser limiters are a different tool (limit travel) than a full VVT delete. Match the cam kit instructions — if your MMX cam listing specifies VVT strategy, follow that.

Who should I call for fitment before I order?

Phone (sales & orders): 276-666-1934
Contact form & hours: Contact MMX
Have ready: year, make, model, engine (5.7 / 6.1 / 6.4 / 6.2), car vs truck, automatic vs manual, and whether the engine still has MDS / stock cam.