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Toyota Celica GT-Four ST205 Performance Tuning Guide

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Table of Contents


Launched in 1994, the ST205 stands as the third and final generation of the Celica GT-Four series, with production ending in 1999.

The Celica GT-Four ST205 is renowned for its unique blend of power, precision, and performance and has recently appreciated in value making it a valuable investment for car enthusiasts.

At the heart of the ST205 is a robust 2L 3S-GTE turbocharged four cylinder engine. With a power output of approximately 255hp in the Japanese version, it makes for a formidable contender on both road and track.

The car employs a full-time all-wheel-drive system, offering superior traction and control – a testament to its roots in the World Rally Championship.

While undoubtedly an icon and offering great performance even by today’s standards, many owners will have the itch to try and extract more performance out of it. 

Whether it’s more power, better handling performance or additional stopping power, we’ll cover it all in this article!

Performance Exhaust

A great way to improve the performance and sound of the ST205 is to fit a more free flowing aftermarket exhaust.

By reducing the back pressure and facilitating an easier path for the exhaust gases to exit, you can get a livelier throttle response and better power output.

On top of the performance benefits, you will also get a nice throaty and deeper exhaust tone that can make putting the foot down on the gas even more addictive.

You can choose to replace the exhaust in sections or you can buy a full free flowing exhaust which is also sometimes referred to as a “turbo-back”.

To minimise the restriction and backpressure, the first section you will want to upgrade is the downpipe and catalytic converter section. A 3 inch bore diameter is a common upgrade option. 

When shopping for a downpipe, you will see options for “catless” or with a high flow sports cat. Catless downpipes won’t pass emission tests and as such aren’t road legal however will provide the least amount of restriction.

To keep your ST205 road legal, you will need to have a high flow sports cat fitted after the downpipe. Some downpipes come with these with them and these systems still provide good performance gains while remaining road legal.

After this section of the exhaust the next section you will want to replace is the backbox section. This is also often referred to as the “cat-back” section. Responsible for muffling the sound, the standard cat-back can pose a restriction and hinders power output.

Replacing the standard cat-back with a performance one can unlock a lot of extra sound from the exhaust.

Panel Filter

Panel filters can enhance the volume of air flowing into the engine. 

The result?

Your Celica will have more power at its disposal and a more responsive throttle.

Panel filters are designed to fit exactly into the existing air box of your Celica, making replacement or maintenance fast and simple as opposed to cone filter alternatives. 

Cone filters/cold air intakes are popular amongst owners who want the most induction sound possible. While producing a nice growl on the throttle and letting you hear the turbo better, cone filters are susceptible to heat soak on these cars.

As such, they aren’t as efficient at drawing in cool air as panel filters are. 

If you are after an increased induction sound as well, a quality aftermarket panel filter can provide a slight increase in this area too so don’t worry.

Boost Controller

With a boost controller, you can manually turn up the boost to increase the turbo speed and generate more power.

You will see the  benefits from this upgrade the most when you have other breathing modifications fitted to the car like a downpipe and intake. 

17psi tends to be the upper limit that most owners will go to safely. After this, fuel cut tends to kick in.

Some people run a fuel cut defender however this isn’t advised for engine safety.

It’s important that your engine and turbo is in good working order before turning up the boost. This goes for other modifications as well but especially for this. 

With a boost controller, free flowing exhaust and intake you can expect to see 300bhp from a healthy ST205.

There are various boost controllers available from manufacturers like Greddy, HKS and Apexi.

Hybrid Turbo

If you have exhausted all the other primary power mods such as an exhaust, panel filter, and boost controller and want a fair bit more power, then a hybrid turbo might be what you’re looking for.

It’s a good idea to have a power figure you want to achieve in mind before pursuing this route.

It’s also important to consider the safety of the internals of the engine when going for large power figures. The standard internals are strong when ran with bolt-on mods but aren’t invincible.

If you are aiming or over 350bhp, consider looking at forged pistons and for over 400bhp then you will want to upgrade the rods too.

The S148 hybrid turbo is a popular option amongst ST205 owners and is capable of running 1.6 bar of boost and producing over 400bhp with the right setup and supporting mods.

Polyurethane Bushes

Upgrading to poly bushes is a simple and often overlooked upgrade that can enhance the handling of the Celica significantly. 

Due to the age of the car, you may find some of the stock rubber bushings worn down and due for replacement. This is a great time and excuse to upgrade to polyurethane bushes. 

Polyurethane bushes are firmer than rubber bushes. This additional stiffness makes the suspension better at absorbing bumps and shocks.

As a result, your ST205 can stay level, maintaining better contact with the road and producing improved handling and stability.

Due to the additional stiffness, they can also help decrease body roll to improve handling on those tight corners. 

You can get them for various components like the rear hub and rear subframe on eBay.

Rear Anti-Roll Bar

If you like to tackle windy back roads or track your ST205, then a stiffer rear anti roll is a great handling upgrade that makes a massive difference. 

The stiffer anti-roll bar reduces the tendency for one side of the car to lean more than the other during turns. This minimization of body roll results in a stable and flat ride, making handling smoother and more predictable.

With a stiffer rear anti roll bar, the tendency for understeer is also reduced. This encourages oversteer more when pushing on, which can be add a whole new engaging dimension to your driving experience. 

Whiteline offer a great rear anti roll bar on eBay for the ST205 (also compatible with the 185) which has 3 points of adjustment so you can dial it in to suit your preferences. 

ST205 Whiteline Anti Roll Bar

Whiteline Rear Anti-Roll Bar

For the Celica ST205

Brake System Upgrades

Now that we have discussed increasing the power and handling performance, let’s talk about the last part of the equation. 

Stopping power!

The type of brake upgrades you decide to do will largely depend on how you use your Celica. The needs of an ST205 that is primarily used for track driving will be different to that of one that is used as an occasional weekend car. 

Starting with the basics, the first place to start is with the brake pads and brake fluid. 

Under intense driving conditions such as those on a race track, you may find that the stock brake pads aren’t up to the task. Brake fade is something you will likely notice after repeated hard braking in which the brakes lose their braking ability due to the build up of heat.

You may also find in track conditions that the brake fluid can start to boil which can severely affect braking performance.

As such, upgrading to a set of aftermarket performance pads such as EBC or Ferodo can make a big difference and you will find them a lot more durable and consistent for performance based driving.

On top of the brake pads, you should opt for high temperature brake fluid such as Motul RBF600. 

While upgrading the brake fluid, you may also want to upgrade the brake lines to braided steel. These aren’t prone to swelling like old and worn standard brake lines might be and can provide a more confident and consistent brake pedal feel.

If you are wanting ultimate braking performance and are using the car primarily for track use then you can look at a big brake kit.

These are the more expensive brake upgrades you can do however will undoubtedly provide the most superior stopping force. Most likely overkill for road use but good for the track.

You can get big brake kits for the ST205 from manufacturers like K-Sport on eBay.

EBC YellowStuff Front Brake Pads

For the Celica ST205

Motul RBF600 Brake Fluid

For the Celica ST205

Finishing Thoughts

The Celica ST205 stands as a testament of a bygone era which blends history and performance brilliantly.

While the standard power it outputs isn’t an awful lot by today’s standards, the ST205 offer’s a great foundation for improving the performance further. 

The engine’s strong internals mean it can handle additional power comfortably, and there are a host of handling mods to improve the already impressive cornering abilities of the 4 driven wheels.

While it can be exciting wanting to further bolster the performance, it’s important to remember that these are old cars now. That doesn’t mean you shouldn’t tune or modify them, but ensure the engine and the car is in good working order before investing in performance enhancing mods to maximise reliability. 

Happy modding!