Stage 2: Basic Modifications
[MA70S2]
Before you enter this stage, consider what you want. Do you REALLY want to stay N/A? If you want a LOT of power, then you can't expect an N/A to do that for you. Turbo is obviously the way to go, and if you want to go turbo, there is another sticky that's in this section that can help with that.
Intake- The stock intake in itself is a good flowing cold air intake, and the helmholtz resonator (intake resonator) is actually good for performance and should not be removed. The only thing that should be removed is the accordian section, and it should be replaced by something such as an aluminum pipe. This will get your engine breathing better due to smooth flow. Also if you decide to change out the stock filter, go for an AEM DryFlo as those are currently the best filters on the market because they offer good flow AND filtering.
Exhaust- One of the most restrictive parts of the Supra is the Exhaust System. By replacing the stock exhaust, you'll have a noticeable difference in power. The stock exhaust is basically a crush bent 2 inch inner diameter exhaust system with a restrictive catalytic converter, and a restrictive muffler. Basically, get better flowing mufflers and larger diameter tubing. Decide what's best for you by listening to general consensus. The general consensus is to go 2.5 inch, but if you want to go turbo, you can go 3 inch as well without suffering too many negative effects other than noise (but that can be stopped if you get HUGE mufflers/resonators)
Header- Technically, this is part of the exhaust, but people consider it a seperate part since the above is a "catback". This mod is supposed to free up the exhaust more, but keep in mind these aftermarket headers will not immediately fit on your Supra unless you get someone to weld and fit it on. Changing this will make your car louder, and from what I recall, it will make your engine bay much hotter unless you somehow keep the heat in, whether you're using header wrap or ceramic coating them. The stock design is pretty good (although it does need improvements. Along with the fact that it is cast iron and heavy), so this mod is only recommended if you're going for that extra push.
Stage 3: Semi-Basic Modifications
[MA70S3]
Well, the most cost effective way to go is Intake/Headers/Exhaust. What do you do after that? You can do a number of things.
Lightweight Driveshaft- a lightweight driveshaft will reduce the rotational mass, which will in turn, make it much easier to accelerate. There have been dynos that say horsepower is gained, for example,
Piratetip's car had an increase in power. The power is gained not due to extra power, but due to power being "freed up" due to the lighter rotational mass. Most lightweight 1 piece driveshafts are 10-14 lbs, and the stock driveshaft is around 32-34 lbs. The loss of rotational mass is HUGE! Keep in mind if the driveshaft is not properly balanced, there will be some vibrations at speeds of around 70 MPH. Lately, there have been developments in lightweight 2 piece driveshafts for those who are worried about driveshaft critical speed.
Lightweight Flywheel- This concept applies only to manual cars and is similar to the concept above. Reduction of rotational mass to free up power.
Lightweight Wheels- Well, most wheels are lighter than the sawblades. Sawblades without tires on them weigh around 24 lbs, so it shouldn't be hard to find stuff that's lighter than them. The concept of this is similar to the above, reduction of rotational mass.
Advanced Timing- Some advance their timing to 12-14 BTDC to gain extra throttle response/power, but keep in mind the "power gain" is minimal (if not even existant). If you do this, you will need to run high(er) octane than 87, or you run the risk of detonation.
Lightweight Parts/Removal of Parts- Well the only thing left to do is replace the heavier parts of the car's body with lightweight parts, or remove the heavier stuff. Some stuff that people remove are the backseats, air conditioner system, and/or power steering. They also remove the spare tire and jack. Some people replace the hood, since the stock hood is very heavy. Common replacement materials for the hood are carbon fiber and fiberglass. Keep in mind removal of parts towards the rear will hurt your traction, but a decent way to solve this problem is to relocate the battery to the rear.
Fuel Controller- Supras stock tend to run rich, so you can take advantage by tuning the Air/Fuel Ratio to gain a few horsepower. The ideal Air/Fuel Ratio (AFR) at Wide Open Throttle (WOT) is 12.5:1.
