The Top 6 Lexus IS300 Performance Upgrades. The Lexus IS300 has been on the market since 2000. It is currently in its third generation, but in the United States, Lexus skipped the second generation in favor of the IS350. After 2005, production of the first generation was halted, with IS300 production resuming in 2016 as part of the third generation.
The 2JZ-GE engine, the non-turbo version of the legendary 2JZ-GTE, is a 3.0L straight-six producing 217hp and 218lb-ft. of torque in first-generation models. The 8AR-FTS engine, a 2.0L turbocharged inline-4 producing 241hp and 258lb-ft of torque, was added to third-generation models.
The modifications we recommend differ because one engine is naturally aspirated and the other is turbocharged. This guide will be divided into two separate articles. This guide will concentrate on the naturally aspirated 3.0L IS300 from 2000 to 2005.
If you have a 2016 or later third-generation IS300, check out our IS300 2.0T Performance Mods Guide.
3.0L 2JZ-GE IS300 Mods
Among the best IS300 mods are:
- Intake
- Headers
- Y-Pipe
- Exhaust with a catalytic converter
- Exhaust cam gear adjustment
- ECU tuning
We’re concentrating on the best bolt-on IS300 modifications. The addition of forced induction is one item missing from our list. Because the 2JZ-GE is based on the same platform as its more powerful sibling, it can handle power and boost well. Turbo kits are a bit more advanced and detailed, so we’ll save that for a separate guide.
The first-generation IS300 also had two transmission options: a 5-speed manual and a 5-speed automatic known as the e-shift transmission. Manual versions will dyno around 180whp bone stock, while eshift versions will dyno around 170whp bone stock.
Considerations for the IS300 2JZ-GE Turbocharger
The six best IS300 mods listed here will increase your power to around 220-230whp for manuals and around 210whp for eshifts. It is possible to exceed those limits and remain naturally aspirated, but it is prohibitively expensive. A stroker kit, meth injection, an aggressive tune, and possibly some nitrous will be required. The stroker kits cost around $7.5k, so we’ll ignore this for the time being.
If you want more than 230whp, adding a turbocharger is the best option. If you intend to add a turbocharger in the future, we recommend skipping the majority of the mods on this list. When you add a turbo, your entire exhaust system will change, and your car will need to be re-tuned, so adding headers and y-pipes is a waste of money because they will eventually be obsolete.
If you do intend to install a turbocharger, it is best to spend your money on suspension, braking, tires, and other handling modifications that will be more necessary with a high horsepower vehicle.
Also, keep in mind that adding a turbo kit will cost you around $5,000 on the low end for a budget setup and up to $10,000+ for a proper setup once you add the boost controllers, timers, widebands, fuel management systems, upgraded injectors, full exhaust systems, and so on.
1. IS300 Cold Air Intake Modifications
An upgraded intake is one of the simplest first modifications to almost any car. While adding an intake to an otherwise stock IS300 will not provide significant performance gains, it will after the other mods mentioned are installed. More combustion is required to generate more power, and air or oxygen is a critical component of combustion.
An intake will probably add 2-3whp to a stock 2JZ-GE. When combined with the other IS300 bolt-on mods, it will provide a 7-10whp boost. So, while it may not be the “best” first mod, it is an essential one and one of the least expensive for beginners.
For the IS300 3.0L, there are several intake options. They are all nearly identical and provide the same benefits.
Related : The 5 Best Honda Civic 1.5T Upgrading Options
IS300 Cold Air Intake Advantages
- When fully modded, it produces 7-10whp and wtq.
- Improved air flow
- Sounds of cool intake
IS300 3.0L Intakes That Work
- aFe
- HPS
- K&N
2. Headers for the Lexus IS300
One of the best standalone mods for the 2JZ-GE is headers. More power translates to more exhaust gases. When more power is added, the stock headers become extremely restrictive, causing a buildup of backpressure within the engine. Backpressure causes exhaust gases to seep back into the combustion chamber, resulting in less oxygen in the combustion chamber and, as a result, less power. Headers will also help reduce exhaust gas temperatures and engine temperatures, making them an excellent mod for reliability.
Aside from making your engine run better, headers can increase power by about 10whp and 10wtq due to reduced backpressure.
Headers come in a variety of prices, ranging from $800 HKS headers to $100 China headers. Everyone has an opinion on which are the best, but the most important thing is to get a set of headers that properly bolt to the y-pipe. Many header options include Y-pipes, but others do not. Headers are just piping, so I don’t mind if you go cheap, but make sure the fitment is good and stick with something made of 304 stainless steel to prevent rusting.
Advantages of IS300 Header Performance
- Power gains of approximately 10whp and 10wtq
- Exhaust note is slightly louder.
- Exhaust backpressure has been reduced.
- Increased exhaust flow
Catalytic Converters are a type of catalyst.
In the IS300, catalytic converters are housed in both the headers and the Y-pipe. Delete both of these cats to gain the most power because they are primarily responsible for the restriction. The catch here is that deleting catalytic converters is against the law. High-flow cats are an alternative, but they are more expensive and options are limited due to the age of these 2JZ-GE engines. For high flow catted options, the power difference is probably about 3whp less.
3. 2JZ-GE Y-Pipe Modifications
The Y-pipe bolts directly to the headers, connecting the headers to the exhaust’s cat-back section. 2JZ-GE headers are made up of two pipes, each of which houses three cylinders of exhaust gases. The y-pipe is so named because it connects to the two header flanges before combining into a single pipe that bolts to the cat-back exhaust.
Because it houses a catalytic converter and sits behind the headers, the Y-Pipe is the second most restrictive part of the exhaust. As a result, upgrading the y-pipe can help reduce backpressure within the exhaust system while increasing power. Because the y-pipe restriction is further away from the engine, it provides slightly less power gains than the headers. When using a catless option, it still provides a solid 8whp.
IS300 Performance Y-Pipe Advantages
- Gains in horsepower and torque are approximately 8whp.
- Exhaust note is slightly louder.
- Improved exhaust flow and lower backpressure
As previously stated, simply ensure that the y-pipe you purchase is properly bolted to the headers.
4. IS300 Exhaust Cat-Back Upgrade
To be honest, unless you want louder exhaust sounds, a catback exhaust system is probably the least worthwhile mod on our list. Catalytic converters are the most expensive exhaust component and provide the least amount of power gain. Having said that, they do reduce some exhaust backpressure and produce about 2-3whp.
Exhaust systems, like headers, are available for $150 and $500. They’re all the same, but choosing your exhaust brand is more important than headers. Headers will not add much extra sound to the exhaust, whereas a catback will. Choosing a cat-back exhaust for the IS300 boils down to personal preference and aesthetics.
From a performance standpoint, I usually advise people to save the money and spend it elsewhere. Go for it if you want the sound. Otherwise, unless you want to squeeze every last bit of power out of the 2JZ-GE, your money is better spent on suspension or handling mods.
3.0L Cat-back Exhaust Advantages
- Torque and 2-3whp
- Exhaust note that is louder (maybe good maybe bad)
- Backpressure has been reduced (minimal)
5. IS300 Exhaust Cam Gear Adjustment
An upgraded exhaust cam gear is the most unique and likely advanced mod on our list. An exhaust gam gear controls the timing of the 2JZ-exhaust GE’s valves. The adjustable cam gears were designed primarily for use with aftermarket camshafts with higher lift, but they can also benefit IS300s with stock camshafts with bolt-on mods. The gear allows you to adjust valve overlap, which is beneficial for NA cars.
It is debatable whether an exhaust cam gear increases power or not. What is known, however, is that it improves the power curve and provides more consistent power and acceleration. Dyno charts show gains in the 6-8whp range, but most owners are more concerned with power curve improvements than power gains. With an adjustable exhaust cam gear, people with turbocharger setups have seen gains of up to 20whp.
Most people recommend setting the exhaust cam gear to -4 on a modded IS300 with stock cams for the best performance and gains.
Advantages of Adjustable Exhaust Cam Gear
- Gains of 0-8whp and similar torque gains
- Enhanced power curve
- Improved acceleration
- Power that is more consistent and carries to the redline
- Improved throttle response
6. IS300 ECU Tune
The final but most important mod to tie everything together is a tune. Tunes modify the ECU and variables such as fueling, timing, and so on to boost power and performance. Tunes are especially important after mods are installed because the stock ECU tune isn’t optimized for more air flow, less backpressure, and other factors.
Unfortunately, flashing the stock ECU on these vehicles is not an option. The Apexi SAFC 2 was the previous tuner of choice, but it is no longer manufactured as far as I know. Today’s options include purchasing a standalone ECU, which is quite expensive and rather advanced in terms of user friendliness. We recommend collaborating with a tuner and conducting additional research and specifics on the options available. This will be covered in its own post later on.
A standalone ECU is also required for adding a turbocharger, so whether you plan to add FI or stick with NA, it’s a good investment. Haltech, MaxECU, AEM, Link, ECU Masters, and other brands are available on the market.
Advantages of a Standalone ECU
- Gains in horsepower and torque of approximately 10whp
- Gains from all other mods mentioned have improved.
- Improved engine dependability
- Power curve and overall performance improvements
IS300 2JZ-GE Power Capacity
The mods on this list will increase your horsepower to around 225whp. This is about the most you can expect without spending a lot of money or using forced induction. The world record NA 2JZ-GE has 320whp, but the owner has reportedly invested $20k-$25k in the build, which is simply not worth it.
What about with a turbocharger? The 2JZ-GE can handle about 400whp on the stock block with stock internals before investments in internals and block strengthening are required. While it can reach 400whp, it is generally agreed that 350whp is the safe limit without compromising reliability. Even 500whp+ is easily achievable, but will necessitate some costly upgrades.
Summary of Lexus IS300 Modifications
If you want to spend a few thousand dollars on a 225whp IS300, go ahead. However, it is widely agreed that adding forced induction via a turbo kit is the best way to increase power in the 2JZ-GE. These engines can handle more than twice the power they produce out of the box, but turbocharging is the only way to achieve those levels of power gains. These engines simply do not mod well when left NA, despite the fact that an extra 40whp over stock isn’t bad.
One thing to keep in mind is that without a proper tune, you are unlikely to experience the benefits mentioned in this article. Remember that the power levels listed are for a fully modified IS300. Expecting 10whp from an intake on a completely stock car is unrealistic. Mods complement one another and build on one another.
Overall, the IS300 has a lot of tunability. The caveat is that all of the tuning potential is in turbocharging, and a proper turbo setup will cost you $8k-$10k.
