Engine & Power · Buyer's Guide

VVT & MDS Delete

VVT (Variable Valve Timing) and MDS (Multi-Displacement System) are factory technologies. VVT adjusts cam timing for efficiency; MDS shuts down 4 of 8 cylinders during light cruising. Both MUST be disabled or controlled when installing an aftermarket camshaft — the new cam profiles are incompatible with these systems. A VVT limiter controls cam phaser movement, and MDS delete plugs seal the oil passages that fed the deactivating lifters. Without these, expect oil pressure issues and erratic engine behavior.

Recommended Picks

A starting point for your build, sorted by budget.

Best ValueMost affordable in this category
Comp Cams MDS Delete Plug Kit (4-pack)

Comp Cams

MDS Delete Plug Kit (4-pack)

$25
Mid-Range PickBalanced price and performance
Comp Cams VVT Limiter Kit (HEMI)

Comp Cams

VVT Limiter Kit (HEMI)

$45
Premium PickTop-tier brand and performance
Mopar MDS Delete Kit (Complete)

Mopar

MDS Delete Kit (Complete)

$65

All VVT & MDS Delete (3)

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4. CAMSHAFT UPGRADES

What the Cam Does

The camshaft controls when and how far the intake/exhaust valves open. An aftermarket cam with more lift and duration lets the engine breathe better at higher RPM, fundamentally changing the power band and sound.

Cam Stages

Stage Profile Idle HP Gain (6.4L) Street Use
Stage 1 Mild (e.g., BTR 220/228) Smooth +30–50 HP Daily driveable
Stage 2 Moderate (lopey) Noticeable lope +50–70 HP Street/weekend
Stage 3 Aggressive Rough/cammy idle +70–100 HP Mostly performance
Stage 4 Race Very rough +100–120+ HP Track only

Required Supporting Parts (The Master Kit)

Every cam swap on an MDS-equipped engine REQUIRES:

  1. Non-MDS Lifters — MDS lifters will fail with an aftermarket cam profile
  2. Valve Springs + Retainers — Stock springs can't handle increased lift
  3. Pushrods (intake + exhaust) — Correct length for new lift specs
  4. VVT Limiter/Lockout — Control Variable Valve Timing with the new cam
  5. MDS Delete Plugs (qty 4) — Seal oil passages from removed MDS system
  6. Custom ECU Tune — Mandatory for idle, fuel, timing tables

MDS Exception

Manual transmission Challengers (Tremec TR-6060) do NOT have MDS. Skip: MDS lifters and MDS delete plugs. Same for 6.1L SRT8.

Key Brands

  • BTR (Brian Tooley Racing): Stage 1–4 cams purpose-built for Gen III HEMI. Very popular in the community. BTR Stage 1 = 220/228 .590/.580 113.5 LSA.
  • Comp Cams: HRT (Hemi Racing Technology) line. Widely available, good support.
  • Texas Speed (TSP): Known for aggressive stages. Complete kits available.
  • 797 Performance: Complete cam kits for 6.4L with everything included — plug-and-play minus the tune.

Sound Impact

A camshaft is arguably the biggest single change to how the car sounds at idle. A Stage 2+ cam gives the classic "potato-potato" HEMI lope that enthusiasts love.

Site UX Recommendations

  • Error-level warning when cam added to build: "A camshaft swap requires a complete master kit. These are the required supporting parts..."
  • Cam builds should auto-add a "You need a tune" warning.
  • Checklist UI for master kit components when cam is selected.
  • Stage filter (1/2/3/4) on cam listings.