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Lexus LS400 Performance Tuning Guide

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Table of Contents


Introduced in 1989 by Toyota’s luxury division, Lexus, the LS400 was designed to compete with established luxury brands such as Mercedes-Benz and BMW.

Powered by a 4.0-liter V8 engine that produced between 250-290 horsepower and 260-270 lb-ft of torque depending on the model year, the LS400 ensured ample and smooth power delivery.

The car’s design also focused on reducing noise and vibration, ensuring a quiet and comfortable ride.

While designed to be a luxury cruiser, some owners may have the itch to want more from their LS400 in terms of performance. This could mean extracting some more power from the engine or perhaps upgrading the handling to reduce body roll.

Regardless of what your aims and objectives are, lets take a look at the best proven and cost effective ways to increase the performance of your beloved LS400!


The LS400’s naturally aspirated engine offers smooth and consistent performance, focusing more on driving comfort and enjoyable experience rather than thrilling power output.

While it is possible to make minor enhancements like optimizing the engine’s configuration or upgrading the intake and exhaust systems, these modifications would not lead to substantial power improvements comparable to what a turbocharger or supercharger would bring to the table.

If you are looking for a serious step up in power, forced induction is what you need!

The first question you will likely ask yourself is “should I go with a turbocharger or a supercharger?”

Superchargers, being mechanically driven by the engine, provide a consistent power boost throughout the rev range. This provides a smooth and linear power delivery synonymous with the operation of the standard engine on the LS400. Ideal if you like your low end torque.

On the other hand, turbochargers utilize exhaust gases to generate more power. Turbo’s produce their power higher up in the rev range, and tend to allow for more significant power gains. 

There aren’t really any tailor made turbo or supercharger kits out there made specifically for the LS400, however many owners have successfully added forced induction to these engines. 

As such, a fair amount of custom work and tinkering is required to get it all running properly and reliably. Depending on how much boost you plan on running, you may also need to upgrade the engine internals to cope with the additional power. 

Unless you are mechanically minded, speak to a local tuning shop who have experience with the 1UZ engines who can do some of the work for you. 

Keep in mind that you will need various supporting mods like an aftermarket ECU, intercooler, upgraded fuelling and more so budget accordingly. 

Air Intake Mod

A popular mod among owners to increase power and induction noise is to modify the stock air filter housing. By removing the front of the housing, you can draw in more air leading to better air flow and more sound.

The only real drawback to this modification is that the air filter will get dirtier faster so you will need to keep an eye on it more regularly than you otherwise would. Definitely still worth it though!

If you don’t want to modify your stock air filter housing, then you can always opt for a cold air intake. While these can produce some nice induction noise on the throttle, they don’t tend to increase performance in theses cars. 

Headers & Sports Cats

One of the most effective performance mods you can do is to install a quality set of aftermarket headers. 

These optimized exhaust manifolds are designed to free up exhaust gases, allowing for better airflow throughout the entire system. This results in increased power and torque. 

In addition, aftermarket headers enhance the exhaust note of your LS400, producing a deeper and more aggressive growl. This auditory upgrade will not only turn heads but give you the satisfaction of experiencing that visceral V8 under the hood.

After the headers we have the catalytic converter section. Responsible for reducing harmful emissions, this section can be a hinderance to performance. 

You can bypass this with a straight through decat pipe however this isn’t road legal. To keep your LS400 road legal while freeing up some performance gains, you can look into replacing the standard catalytic converter with a sports cat. 

Sports cats are designed to improve performance by freeing up the exhaust gas air flow while remaining compliant for emissions tests. 

Aftermarket Muffler/Muffler Delete

The final part of the exhaust equation is the muffler sections towards the rear. There are 4 mufflers in total! This is the section that is responsible for controlling the sound you hear coming from the tailpipes. 

As standard, the exhaust is rather muffled which is to be expected with the type of luxury cruiser it was built as. It can also be quite restrictive, and upgrading to a free flowing muffler (or no muffler altogether!) can yield nice power gains. 

While many install a sports muffler/cat-back to experience the thrilling symphony of the V8, we will be focusing on the performance gains you can get from this mod. With these cars being around 25+ years olds now, many of the original muffler sections may have cracks or structural rust. As such, it can be a good excuse to upgrade to a performance muffler as preventative maintenance. 

The other alternative to upgrading to a sports muffler is to remove the standard mufflers altogether! This is often referred to as a “muffler delete”. While this will unlock some ponies,  it will obviously increase the sound of your LS400 quit significantly.

This may be exactly what you’re after if you’re craving that deep rumble of the V8, however if you enjoy your quiet cruising on motorways then this may not be the solution. It’s also worth bearing in mind that deleting the muffler sections can introduce an annoying droning sound into the cabin at motorway speeds. Some owners don’t report this as much when the standard resonator has been kept.


The installation of coilovers offers a significant improvement in both performance and aesthetics. Coilovers provide a customizable suspension system, allowing you to fine-tune your Lexus’s handling and ride height to your preferences.

With the adjustability of coilovers, one can achieve a more aggressive stance while also enhancing its road presence.

In terms of performance, coilovers deliver better handling and cornering capabilities, as they reduce body roll. This results in a more responsive and stable driving experience, particularly during high-speed maneuvers or on winding roads. 

The ability to adjust damping and spring rates enables you to optimize the suspension setup to maintain the comfort of the LS400 while improving performance. Due to it being known for it’s comfort and luxury, many owners want to ensure the smooth suspension and driving experience is maintained. A high quality and well dialled in set of coilovers can allow this. 

Finishing Thoughts

While tunable, the LS400 engine is not designed to deliver massive power gains without investing in a turbocharger or supercharger.

That doesn’t mean you can’t get some noticeable performance gains that delivery a more responsive driving experience. For example, a more free flowing exhaust can make your LS400 feel more nippy throughout the rev range and deliver a lovely exhaust note. 

Just don’t expect to significant increase your power output by fitting a few bolt on mods. 

Happy modding!