Supra FAQ page 5

93.5-95 Supra Twin Turbo 6-speed specifications (most info applies to 96-98s as well):

Engine:
Type: Intercooled, sequential twin turbo, aluminum head w/ iron block, inline-6
Valvetrain: Belt-driven dual overhead camshafts, 4-valves per cylinder
Displacement: 183 cu in. / 2997 cc
Bore x stroke: 3.39 x 3.39 in. / 86.1 x 86.1 mm
Compression Ratio: 8.5:1
Horsepower (SAE): 320 hp @ 5800 rpm
Torque: 315 lb-ft @ 4000 rpm
Maximum Engine Speed: 6800 rpm
Fuel Injection: Electronic, sequential multi-port
Emissions controls: 3-way catalytic converter, feedback fuel-air-ratio control, EGR
Turbochargers: 2x Hitachi CT12
Wastegate: Toyota (on primary turbo only)
Maximum boost pressure: 11.6 psi
Fuel Required: Premium unleaded, 91 pump octane
Oil Capacity: 5.3 qt.

Drivetrain:
Transmission 6-speed manual:
Gear Ratio Overall ratio (rpm) mph
1st 3.83:1 12.50:1 (6800) 41
2nd 2.36:1 7.71:1 (6800) 66
3rd 1.69:1 5.51:1 (6800) 92
4th 1.31:1 4.28:1 (6800) 119
5th 1.00:1 3.27:1 (6800) 156
6th 0.79:1 2.59:1 (5500) 158

Final-Drive Ratio: 3.13:1, Torsen limited-slip

Chassis & Body:
Configuration: Front engine / Rear drive
Type: Unit construction with front subframe and rear rubber-isolated subframe
Body material: Welded steel and aluminum stampings

Brakes:
Front: 12.7 x 1.2-in. vented discs, 4-piston calipers
Rear: 12.8 x 0.6-in. vented discs, 2-piston calipers
Assist type: Vacuum, 4-channel ABS
Total swept area: 573 sq in.
Swept area/ton: 332 sq in.

Wheels / Tires:
Wheels: Cast aluminum: F 17 x 8.0 in., R 17 x 9.5 in.
Tires: P235/45ZR-17 f, P255/40ZR-17 r

Suspension:
Front: Upper & lower A-arms, coil springs, tube shocks, anti-roll bar
Rear: Upper A-arms, dual lower lateral links, semi-trailing links, coil springs, tube shocks, anti-roll bar

Steering:
Type: Rack & pinion, power assist
Overall ratio: 17.5:1
Turns, lock to lock: 3.0
Turning circle: 35.4 ft

General Data:
Curb weight: 3480 lb
Test weight: 3620 lb
Weight dist. (w/ driver): f/r, % 52 / 48
Wheelbase: 100.4 in.
Track: f/r 59.9 in. / 60.1 in.
Length: 177.7 in.
Width: 71.3 in.
Height: 50.2 in.
Ground clearance: 5.5 in.

Basic warranty: 36 mo / 36,000 mi

Interior:
SAE volume: front seat 52 cu ft
SAE volume: rear seat 20 cu ft
SAE volume: luggage space 10 cu ft
Seating capacity: 2+2
Front seats: Bucket
Seat adjustments: fore and aft, seatback angle, rear height
Head room: f/r 38.0 in. / 33.0 in.
Seat width: f/r 2 x 19.0 in. / 2 x 18.0 in.
Front-seat leg room: 43.5 in.
Rear-seat knee room: 24.5 in.
Seatback adjustment: 70 deg
Seat travel: 9.5 in.
Restraint systems: Front Manual 3-point belts, driver and passenger airbags
Restraint systems: Rear Manual 3-point belts
General Comfort: Excellent
Fore-and-aft support: Excellent
Lateral support: Good

Interior Noise:
Idle in neutral: 48 dBA
Maximum in 1st gear: 73 dBA
Constant 50 mph: 63 dBA
Constant 70 mph: 68 dBA

Instrumentation: 180-mph speedometer, 8000-rpm tachometer, coolant temperature, and fuel level

Acceleration:
0-30 mph 2.2 sec
0-40 mph 2.9 sec
0-50 mph 4.0 sec
0-60 mph 5.0 sec
0-70 mph 6.5 sec
0-80 mph 8.0 sec
0-90 mph 9.9 sec
0-100 mph 11.8 sec
0-100 feet 3.0 sec
0-500 feet 7.5 sec
0-1320 feet 13.5 @ 107.0 mph

Fuel Economy:
Normal driving: est. 19.0 mpg
EPA city/highway: est. 18/23 mpg
Cruise range: est. 330 miles
Fuel capacity: 18.5 gal.

Braking:
Stopping distance from 60 mph: 120 ft
Stopping distance from 70 mph: 160 ft
Stopping distance from 80 mph: 225 ft
Control: Very good
Fade: None
Pedal effort for 0.5g stop: 16 lb
Fade, effort after six 0.5g stops from 60 mph: 21 lb
Brake feel: Excellent
Overall brake rating: Excellent

Handling:
Lateral Acceleration (200-ft skidpad): 0.98g
Balance: Mild understeer
Speed thru 700-ft slalom: 66.0 mph
Balance: Mild understeer

What are the first engine modifications I should perform?
I recommend starting with raising the boost of the stock turbos to roughly 18psi. This will require a quality boost gauge and a boost cut eliminator (GReddy BCC). You will achieve 15 or so PSI with the stock Down Pipe in place. This will provide an addition of approximately 30rwhp. After those modifications are completed, it would be a logical next step to install the Down Pipe and Cat-Back Exhaust at the same time. You will now be at full BPU™.

What do all the various "Free Mods" do?
There are many different "free mods" for the Supra TT. I will cover just a few of them here. The ones I will cover fall into three categories, boost control, EGR disabling, and TTC or True Twin Conversion.

Three of the boost control mods are: Bleeder-T Mod, Clamp Mod, and the VSV Bypass Mod. Each of these modifications raise boost levels without the use of a boost controller. But you have to keep a close eye on your boost gauge, and make sure they are not allowing the turbos to boost too high (18psi is a safe level).

The next mods, are the true twin conversion mods (or TTC). This modification disables the Sequential twin turbo operation, and causes the turbos to run constantly in parallel (both on at the same time). This is supposed to allow for slightly better mid-range power (before the secondary turbo would normally come online) and allows for a smoother power band, without the abrupt boost increase caused by the transition from primary to secondary operation. However, this does noticeably decrease low-end power, and increases exhaust noise levels, and therefore may not be desirable on the street. Two types of the TTC mod are, the traditional TTC mod which includes 2 methods, wiring the actuators, or installing a one way valve, and the Electronic TTC mod (ETTC).

The last mod I will discuss is the EGR mod. This disables the Exhaust Gas Recirculation system, which is meant for emissions, and therefore, this modification is for off-road use only. This mod is supposed to prevent the super heating of the number 5 and 6 cylinders, which may cause burnt valves.