read this, it would be good for you to follow. like i said a turbo upgrade should be the last thing on that car.
Stage 1:
Intake, 235bhp @ 7psi[/size]
The first thing to do in increasing any engine's performance is to make sure it can flow plenty of air. The simplest way to help an engine breathe better is by installing an aftermarket intake. There are many different brands out there, but Apexi performed the best in this test. For hints on installing a full intake kit, please see this tech tip. While you are at it, I also recommend the SOGI cold-air intake mod.
Stage 2:
Cat-back, 250bhp @ ~8psi
Continuing with the theme of better breathing, the next step is to install a cat-back exhaust. There are even more brands and styles of exhausts than intakes, so take your time and find one which best fits your needs for flow, looks, and sound. If you live in an area where corrosion is a problem, you probably will not want to settle for anything less than a full stainless system.
Stage 3:
Downpipe/elbow/primary cat or test pipe, 280bhp @ ~9psi
If you still want more power, then its time to replace the restrictive stock downpipe, turbo elbow, and secondary catalytic converter. This picture shows one of the simpler downpipes, although there are some downpipes that integrate a turbo elbow and test pipe in one unit. For the environmentally concerned, Random Technologies makes a high-flow cat that will replace the secondary cat, but it obviously will not flow as well as a "test pipe." One word of caution -- downpipes are not legal in all states as they replace the primary catalytic converter.
Stage 3.5:
Gauges
While gauges do not increase power, it is important especially if you want to continue modifying. At this point, you're probably already boosting 9 psi, which exceeds the stock boost gauge. Installing a new one, along with an Exhaust Gas Temperature (EGT) gauge is also a good idea. An Air/Fuel ratio gauge is also good, but readings based on your factory O2 sensor are next to worthless so a wideband 02 sensor would be necessary. Other good gauges to consider are water temperature, oil pressure, and oil temperature. If you can afford it, look for gauges with a peak hold feature. These can be very helpful, as you cannot always pay close attention to your gauges when you are driving hard.
Stage 4:
Boost controller, 300bhp @ just under fuel cut
Now that your engine can breathe freely and you can monitor what it's doing, it is time to turn up the boost with a boost controller. There are inexpensive manual boost controllers out there, but I have found it to be a pain to get out and adjust them every time the weather changes. The solution is an electronic boost controller which can not only be adjusted from inside the car, but some can also learn to better control your wastegate allowing the turbo to spool much faster.
Stage 5:
Intercooler and hardpipes, 320bhp @ just under fuel cut
If you still want more power, you will need to replace your stock intercooler and the restrictive stock intercooler piping. Compressing air creates heat, which can lead to detonation. Since you want to turn up the boost even more, you'll need an intercooler that can not only flow better but also do a better job of keeping the air cool. It also is a good idea to replace your factory bypass valve to prevent compressor surge.
Stage 5.5
fuel pump
When you try to boost too high, your ECU will cut fuel momentarily to prevent engine damage. Now that you want to exceed that limit, it is time to upgrade your fuel system. While it is possible to boost a little over fuel cut on the stock fuel system, it is not recommended -- especially if you have your sights set significantly higher. The first step to upgrading your fuel system is to then replace the fuel pump with one that can move more fuel. Walbro and the stock MKIV tt pump are common choices.
Stage 6:
Lexus AFM/550 injectors, 340bhp @ 15psi
One of the most common ways around fuel cut is to use an Air Flow Meter off a Lexus V8. The basic gist is this air flow meter allows some unmetered air through tricking the stock ECU into thinking it is getting less air than it really is. Because the ECU thinks it is getting less air, the boost at which you hit fuel cut goes up. To offset this extra air, 550 injectors replace the stock 440 units. Details on this upgrade can be found here. Recently, PHR has announced they will make a "map ecu" that will allow consumers to use a much less restrictive MAP sensor instead of an AFM. Details on this product can be found here.
Stage 7:
Fuel tuning device and dyno tuning, 375bhp @ 16psi
At this point, the car could benefit from some fine-tuning. Chances are you will be running rich, so an air/fuel controller can lean out the mixture and help further raise fuel cut. There are many options out there, so do a little research and decide on the best unit for your goals. If you must have the best, a standalone is the way to go but it is much more expensive, and is more difficult to tune (chances are you will have to have a professional tune it).
Stage 8:
Upgraded turbo
You have now reached the useable limits of the stock turbo. It is possible to further increase the boost, but the turbo will be blowing such hot air that you will experience diminishing returns. Which turbo you go with will depend entirely on how far you want to take your Supra. If 450bhp or less is ok you can go with an upgraded CT26. 550bhp or less and you can go with a bolt-on hybrid turbo. If that is not enough, then you will be looking at a bigger turbo that will probably involve some custom work. If you do have your sights set that high, you probably know what you’re doing or will be taking the car to a professional.
