Engine & Power · Buyer's Guide

Underdrive Pulleys

Your engine spins several accessories via a belt — the alternator, A/C compressor, power steering pump, and water pump. Each one steals a little bit of horsepower to operate. Underdrive pulleys are slightly smaller than stock, so these accessories spin slower and steal less power. It's a simple bolt-on that frees up 8-15 HP. The trade-off is slightly reduced accessory performance at idle (dimmer headlights, weaker A/C), though most people never notice.

Recommended Picks

A starting point for your build, sorted by budget.

Best ValueMost affordable in this category
BBK Performance Underdrive Pulley Kit (5.7L/6.4L)

BBK Performance

Underdrive Pulley Kit (5.7L/6.4L)

$180+10 HP

All Underdrive Pulleys (1)

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1. COLD AIR INTAKES (CAI)

What It Does

Replaces the restrictive factory air box with a larger-diameter intake tube that pulls cooler, denser air from outside the engine bay. Cooler air is denser, which means more oxygen molecules per cubic foot = better combustion = more power.

HP Gains by Engine

Engine Best Brands HP Gain Torque Gain
5.7L R/T HEMI aFe, JLT, K&N, BBK +8–17 HP +10–20 lb-ft
6.4L Scat Pack HEMI aFe, JLT, Mopar +15–18 HP +15–22 lb-ft
6.2L Hellcat aFe Carbon Fiber +25–37 HP +22–36 lb-ft

Key Brands & Products

  • aFe Power: Momentum GT, Magnum FORCE Stage-2. Known for rigorous dyno testing. Carbon Fiber option for Hellcat is premium.
  • JLT Performance: Popular series 2 CAI — strong mid-range torque focus.
  • K&N: Typhoon system — well-known brand, easy install, good filter longevity.
  • BBK Performance: Budget-friendly, bolt-on in ~30 min, no extra hardware needed.
  • Mopar: OEM-quality, maintains warranty, less aggressive gains.
  • Corsa: Carbon fiber intake option for 6.2L Hellcat.

Install Notes

  • Most CAIs are 30–60 minute installs, no special tools.
  • Some may trigger a check engine light due to MAF sensor sensitivity — tune may be needed.
  • Sealed (enclosed) intakes maintain cooler air temps vs. open filters that can heat-soak.
  • Pairs best with tune to maximize gains — tune alone on stock intake is significant, CAI + tune is better.

Site UX Recommendations

  • Display "Does this require a tune?" clearly on each listing (most do NOT require one for basic install).
  • Show HP ranges by engine size prominently.
  • "Best First Mod" badge — CAI is the consensus #1 beginner purchase.
  • Sound clips: Some intakes have a distinctive induction growl under hard acceleration.