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The Grand Cherokee SRT is fast stock. But the 6.4L HEMI has significant headroom, and a few well-chosen modifications can push it well past 500 horsepower without touching reliability. Here’s what works, what doesn’t, and what order to do it in.
Step 1: Cold Air Intake — +10-15 hp ($250-500)
The single best bang-for-buck modification on the 6.4L. A quality cold air intake adds 10-15 hp, improves throttle response noticeably, and gives the HEMI a better sound under hard acceleration. Completely reversible and won’t void your warranty on other components.
Best options: K&N 57 Series FIPK or Volant Cold Air Intake. Both are direct bolt-ons, no fabrication required. Install takes about an hour.
Install guide: Watch install videos on YouTube — step-by-step walkthroughs available, basic hand tools only.
Step 2: ECU Tune — +25-40 hp ($400-800)
This is where the biggest gains come from. A professional tune optimizes fuel timing, air-fuel ratio, and shift points. On a stock GC SRT with just an intake, a tune typically adds 25-40 hp and 20-30 lb-ft — pushing you well above 500 hp.
Best options: Livernois Motorsports (mail-in custom tuning, highly regarded in the SRT community) or Diablo Sport Trinity 2 handheld tuner for off-the-shelf tunes.
Install guide: Watch tuning videos on YouTube — handheld tuners are plug-and-play via OBD2. Mail-in tunes require a data logger.
Step 3: Catback Exhaust — +5-10 hp ($800-1,500)
The stock exhaust is restrained for a 475hp SUV. A quality catback dramatically improves sound and adds modest power. The HEMI through a free-flowing exhaust is one of the best sounds in the business.
- Borla ATAK — most aggressive sound, loud at startup and full throttle
- Borla S-Type — aggressive under hard acceleration, livable at cruise
- Corsa Sport — similar to S-Type, excellent build quality
Install guide: Watch exhaust install videos on YouTube — requires jack stands or a lift, 2-3 hours.
Step 4: Brake Pad Upgrade ($150-250)
Added power means you need better stopping. The Brembo hardware is excellent but OEM pads fade under repeated hard use. Upgrade pads when you add power.
- Hawk HPS 5.0 — best daily driver upgrade, dramatically better heat resistance
- EBC Yellowstuff — slightly more aggressive bite, great for spirited driving
Pro tip: Always flush brake fluid when swapping pads — fresh fluid has a higher boiling point and costs $50-100 at any shop.
Install guide: Watch brake pad install videos on YouTube — about 1 hour per axle, basic tools.
Step 5: Suspension Tuning ($150-2,000)
- Addco rear sway bar — best value handling upgrade at $150-300, significantly reduces body roll
- Eibach lowering springs — drops 1 inch, sharper turn-in, $300-500
Power Gains at a Glance
- Cold air intake alone: +10-15 hp
- ECU tune alone: +20-30 hp
- Intake + tune combined: +40-55 hp (synergistic)
- Add catback exhaust: +5-10 hp more
- Full Stage 1 (intake + tune + exhaust): ~520-540 hp — up from 475 stock
Community Resources
JeepGarage.org SRT Forum — the most active Grand Cherokee SRT community. Real dyno results, install threads, and owner advice.
YouTube: Jeep Grand Cherokee SRT mods — dozens of mod install and review videos from real owners.
Related Articles
Jeep Grand Cherokee SRT: The Complete Owner’s Guide — Full specs, common problems, and maintenance.
GC SRT Common Problems — Know what to watch for before and after modding.
SRT Diagnostic Tool — Something feel different after a mod? Get a diagnosis.
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