Jeep Grand Cherokee V8

JEEP 6.4L Upgrades at Geelong Performance Centre

At Geelong Performance Centre, we offer a range of upgrades to enhance the performance of your JEEP SRT 6.4L, delivering more power, better sound, and improved efficiency. Stages 1 and 2 are intake and exhaust upgrades, completed in one to two days. Stage 3 is internal engine work — a camshaft and MDS delete package that stands on its own, and takes longer. Here's a detailed look at what each option offers:

Stage 1

Our Stage 1 upgrade begins with the installation of a high-flow K&N Cold Air Intake system. This system boosts engine breathing, increasing power and torque while enhancing the V8's iconic sound. Alongside this, we fit a Pacemaker dual 3" cat-back exhaust system to improve airflow further and elevate the overall driving experience.

Once these components are installed, we perform a custom ECU tune on our state-of-the-art dyno, optimising the engine for power, torque, and fuel efficiency. We fine-tune the vehicle during road testing to ensure that all adjustments enhance performance and driveability. At the end of the process, you will receive a detailed dyno graph showing the gains made in power and torque.

Stage 2

Stage 2 builds on the upgrades from Stage 1, adding more significant improvements for enhanced performance. We install a set of 4-1 headers (extractors) and high-flow metallic catalytic converters. These components are specifically designed to improve exhaust flow, delivering a noticeable increase in power and torque. The headers we use are selected based on the level of modification and application — either Pacemaker's 2" 4-1 headers for supercharged engines or 1-7/8" headers for naturally aspirated setups, both paired with 3" high-flow cats.

As with Stage 1, we perform a custom ECU dyno tune to optimise your vehicle's power, efficiency, and responsiveness. This upgrade delivers a thrilling V8 sound, with deep and resonant exhaust notes, and significantly improved performance. After the upgrade, you'll receive a dyno graph detailing the performance gains.

Stage 3 | Camshaft & MDS Delete

Stage 3 is a standalone package. It isn't an exhaust or intake upgrade — it's internal engine work, and it can be done on its own or alongside any of the upgrades above.

The camshaft is the single biggest limit on how much air a naturally aspirated engine can move. The factory cam in the 6.4 is a compromise built around emissions, economy and cylinder deactivation. We replace it with a performance camshaft matched to your setup, and fit a phaser limiter so cam timing stays stable and predictable once the standard variable timing range is no longer appropriate.

At the same time, we delete the MDS cylinder deactivation system. The lifters that run it are a known weak point on this platform, and they don't suit a performance camshaft. They're replaced with high-performance items and the system is removed entirely.

A camshaft is not a standalone part, and we don't treat it as one. Upgraded valve springs are fitted to control the new profile, and the engine goes back together with heavy-duty pushrods, new gaskets and bolts throughout, and fresh oil and coolant. The vehicle is then custom tuned on the dyno and road tested to finalise the calibration, and you receive a before-and-after dyno graph.

It's worth being clear about what this upgrade involves. It's a multi-day job, not a bolt-on. It changes the character of the vehicle — the idle, the sound and the way it makes power are all noticeably different to standard. Your SRT needs to be in good mechanical condition before we start, and we'll talk through the condition and kilometres of your engine before booking anything in.

If you want a Hemi that sounds like a Hemi and pulls all the way to the top, this is the upgrade that gets you there.

Components Explained:

Cold Air Intake: The K&N Cold Air Induction (CAI) system ensures that your Hemi engine breathes freely. The large-diameter intake path and pod-style air filter reduce airflow restriction, while the enclosed housing helps minimise the intake of hot air from the engine bay, maximising power gains.

Cat-back Exhaust System: The cat-back exhaust system replaces everything from the catalytic converters to the tips of the exhaust. This system uses larger diameter pipes and high-flow mufflers to enhance both sound and performance. Pacemaker Exhausts, a trusted Australian brand for nearly 50 years, manufactures a premium stainless steel dual 3" system, ensuring quality and durability, while delivering a rich and aggressive exhaust note.

Headers & High-Flow Cats: Our Stage 2 upgrade includes 4-1 headers (extractors), which are designed to improve exhaust flow and performance. These headers are available in different sizes to suit both naturally aspirated and blown (supercharged) setups. The high-flow catalytic converters are durable and feature a metal-coated matrix with either 100 or 200 CPI (cells per inch) for maximum efficiency and longevity. This system is engineered to handle the high performance of the Hemi V8.

Camshaft Package: The camshaft controls when and for how long the valves open, and it dictates where in the rev range an engine makes its power. The factory cam in the 6.4 is built around emissions, fuel economy and cylinder deactivation rather than outright performance. A performance profile lifts power through the mid-range and top end, and gives the engine the exhaust note the platform is known for. A cam is only as good as the valvetrain around it, which is why our Stage 3 package includes valve springs, lifters, pushrods and a phaser limiter as standard rather than as optional extras.

MDS Delete: The 6.4 Hemi uses MDS cylinder deactivation to shut down cylinders under light load. The lifters that make this work are a known failure point and they don't suit a performance camshaft. As part of Stage 3 we replace them with high-performance lifters and delete the system entirely — better reliability, better valvetrain stability, and no unwanted switching between modes.

At Geelong Performance Centre, we're dedicated to delivering top-quality performance upgrades for your JEEP SRT 6.4L, ensuring your vehicle performs at its best.

Please note: some models will require a ECU unlock, this is an additional cost. Please contact us for more information.