3.0L Duramax LM2 Performance Upgrade Guide

The LM2 Duramax is only a few years old – it’s natural that the market takes a bit of time to introduce performance parts considering a lot of these trucks are still under warranty. However, in the case of the LM2 the biggest inhibitor to mods and upgrades has been tuning. Up until about March of 2023 no company had been able to crack the 3.0 Duramax’s ECM, meaning there were no tuning solutions available. And performance modifications without tuning don’t tend to yield big performance gains.

Now that tuning is available for the Duramax LM2 we expect the performance aftermarket to kick into high gear on developing parts for the platform. While things are still early tunes are finally available to end customers. Therefore, we’re bringing you our guide on performance upgrades for the LM2. As new products are developed and tuning capabilities progress we will keep this article updated with all of the best 3.0 Duramax mods available.

The Duramax LZ0 is still extremely new and there is very limited aftermarket support there so we will write a separate guide on LZ0 mods once there are options available.

If you’re interested in watching our YouTube video on the LM2 mods, here it is:

Duramax LM2 Engine Limits

Power limits on the LM2 are almost unexplored at this point. So far tuning options are only claiming to add approximately 50whp which leads us to believe that the turbocharger is going to be an initial restriction and require upgrading early on to push bigger power levels. The turbo on the factory LM2 is pretty small and some initial R&D work has found this to be the first bottleneck.

Furthermore, these engines do suffer a few common problems relating to the injectors and the injection pump. We aren’t aware of anyone that has tested the power limits on these yet, but their problems on stock trucks lead us to guess that fueling upgrades will be required as well once the turbo is upgraded.

For reference, a stock LM2 dyno’s approx. 250whp and 400wtq. With the mods we are covering below you will probably be adding anywhere from 50-60whp depending on the tuning. We are confident that the engine is strong enough internally to handle all of these upgrades.

Best 3.0 Duramax LM2 Mods

1. Tuning
2. Cold Air Intake
3. Exhaust
4. Turbo Upgrades (coming soon)
5. Other Supplemental Mods

There are really only 3 modifications that are worth it at this time. We’re going to cover a few additional modifications like intercoolers, piping kits, resonator deletes, and so on but these have yet to yield any worthwhile performance gains. This might change once turbo upgrades and more advanced mods are available, but for now we recommend sticking to tuning, an intake, and an exhaust.

1) ECM & TCM Tuning

HP Tuners is the only software that is capable of actually tuning the 3.0 Duramax at this time. There are some throttle sensitivity products like Edge’s Pulsar LT and Banks PedalMonster – but do not confuse these with tuning.

Engine tuning and transmission tuning is available via HP Tuners and there are a number of companies that are beginning to offer tuning services for them, such as PPEI and RunVSE. The downside is that tuning these components requires the ECM and the TCM to be unlocked. If you aren’t local to a shop offering 3.0 Duramax tuning then you will have to uninstall the ECM and/or the TCM and send it in to have it unlocked.

Tuning is going to range from around $1,500 to $2,000 depending on whether you want to toss in transmission tuning or not. In addition to the tunes and the EMC and TCM unlocking service you will also need a HP Tuners MPVI3 device and 6-10 flashing credits. If you already have a device and credits then you can get the cost down to around $1,000.

Tuning Performance Gains

• Up to approx. 50whp and 110wtq
• Improved turbo spool / reduced lag
• Better throttle response
• Small fuel economy increases
• Overall more efficient + better running engine

2) Cold Air Intake Upgrade

“Cold air” might not be the right term, but the second best upgrade is an intake system. Engines require more air to create more power. And the turbocharger will need more air to help increase it’s efficiency and reduce the stress placed on it from higher boost levels.

An intake upgrade without tuning will usually provide very limited performance gains. However, with tuning the gains from an intake are amplified and produce solid power gains while also taking a bit of stress off of the engine and turbo.

S&B’s intake is the best on the market as of now – and one of the only on the market. It’s also the most affordable at $349.

Intake Upgrade Benefits

• Approx. 5-10whp with tuning
• Improved throttle response
• Faster turbo spool
• More efficient turbo
• Small fuel economy gains

3) Higher Flowing Exhaust System

On turbocharged cars no exhaust system is typically the best exhaust system. The less backpressure present after the turbo, the more efficient the turbo will run and therefore the more power it will make. Usually on turbo engines we recommend downpipe upgrades as they yield the best benefits. For the 3.0 LM2 the only options available are cat-back systems at this time. There are rumors of delete kits available on the market but we are going to refrain from commenting on that.

Once we’re bringing more air in with the intake and bumping power levels up with the tuning, it’s important to be able to get all of this extra air out of the engine is quickly as possible. While it may be small, a catback exhaust system is going to reduce backpressure a bit and help the exhaust gasses flow out more quickly.

Without tuning and an intake an exhaust is only going to be good for sound increases and won’t yield really anything from a performance perspective. However, when tuned it will provide some benefits, albeit small.

Exhaust Upgrade Benefits

• Reduced exhaust backpressure
• Louder exhaust sounds
• Maybe some small horsepower and torque gains

Exhaust kits run anywhere from $500-$1,000+. At these prices this is probably the least important upgrade at this point. An exhaust isn’t going to be needed when only pushing an additional ~50whp but it still will help a small bit. I would prefer a downpipe upgrade but we have to wait until those are available.

4) Turbo Upgrade Kits

It seems like tuning companies are having a hard time getting more than ~50whp out of the stock turbo. We know a few companies are working hard on creating turbocharger upgrade kits but none are ready quite yet.

After the above 3 modifications we suspect an upgraded turbo will be the next best option for the LM2. But we’re going to have to wait a bit longer to see what types of kits become available as well as the supporting modifications that will be required to push power limits above what is currently possible.

Stay tuned as we keep this section updated for future turbo kit developments.

5) Other Modifications

There are a few other options and products available on the market that claim to provide some performance gains. There are also a few upgrades that provide some reliability benefits in keeping engine temps and EGTs down that we’ll discuss. Some of these mods may be worth it, but we don’t believe any of the “power” mods are worth it at this time.

Turbo Resonator Delete

The turbocharger is accompanied by a resonator pipe that is meant to reduce turbo noise. Some companies are making resonator delete pipes and claiming they have performance benefits. All of these upgraded pipes are the same diameter as the factory resonator and the factory unit doesn’t have anything restrictive on the inside of it, just some shielding on the outside to reduce noise.

These are like $80 if you want to give it a try and get some cooler turbo spool noises, but don’t expect anything in terms of performance gains.

Intercooler & Piping Kits

The Duramax LM2 uses an air-to-water intercooler that sits on the top of the engine which makes upgrading it a bit more expensive. An upgraded intercooler is going to run about $1,600 from PPE – they are claiming 17% less pressure drop and a 77% improvement to core air flow, complements of a 2.4x larger core. Additionally, there are a few piping kits but these are more so dress up / aesthetic upgrades at this point.

We do think intercooler upgrades will become important in the future as turbo upgrades become available. However, with the minimal power gains available now dropping $1,600 on an intercooler doesn’t seem worth it. It will help keep engine temps and EGTs lower if you do frequent towing, though. So it could be worth it as a reliability upgrade for heavy towing.

Transmission Cooler & Trans and Oil Pan

All of these upgrades go into the reliability category as they provide no performance benefits. Upgraded transmission coolers run about $350 and claim up to a 45 degree drop in trans temps. Additionally, some owners have reported lower engine temps by approx. 10 degrees by running an upgraded oil pan and trans pan. Again, might be worth it for reliability but won’t offer any performance benefits.

Summary

The aftermarket support for the Duramax LM2 is finally heating up now that the ECM’s have been cracked and tuning is available. HP Tuners software is capable of tuning the LM2 and can provide power gains around 50whp and 110wtq on an aggressive tune. We recommend absolutely coupling an intake with tuning and adding an exhaust system if it is within budget as well.

The turbocharger is the most restrictive factory component so those looking for bigger power gains will need to hold off until turbo upgrade kits are available, which we have heard are underway.

Beyond tuning, an intake, and exhaust there are a few other performance parts on the market like intercoolers, resonator deletes, and piping kits. These upgrades aren’t yet worth it in our opinion but might be in the future. In terms of reliability upgrades, an intercooler will definitely be beneficial in addition to a transmission cooler and both a transmission pan and oil pan. Albeit, these are likely only worthwhile for people who do a lot of heavy towing and need to keep temps down and reduce wear on the transmission.

Ultimately, the market is new and still developing so we will keep this guide updated as more options hit the market.