1989
GM made a new dual catalytic converter exhaust system (RPO code N10) available, freeing up 13% more power from some LB9- and L98-equipped Formulas and Trans Ams; so equipped, LB9 engine output was increased to 230 hp while the L98 increased to 240 hp.
The N10 option remained available throughout the balance of the Third Generation production run, however the L98 powerplant was only available with an automatic transmission, whereas the LB9/N10 combination could only be coupled to a 5-speed manual (RPO code MM5) and a limited-slip differential (RPO code G80) using a 3.45 axle ratio (RPO code GM3). According to a March 1990 (Vol. 35, No. 9) Car and Driver article, when the latter set of options were combined into the 300-pounds-lighter Formula body, which shared same WS6 suspension with the top-end Trans Am GTA, it created a high-performance "sleeper" that could out-perform the heavier Trans Am GTA (even when equipped with the L98 engine) — at a roughly 30% lower sticker price. Although not an exhaustive comparison, these claims would seem to be supported by a simple examination of the weight-to-power ratios of both models: a 230 hp Formula at a curb weight of 3,300 lb. versus a 240 hp Trans Am GTA at a curb weight of 3,600 lb.; the weight-to-power ratio for the Formula is 14.3 lb/hp compared to 15.0 lb/hp for the Trans Am GTA. According to the same Car and Driver article, very few of these "hopped-up" Formulas hit the streets; only about 50 were built each model year, as almost all LB9-equipped Formulas came with an automatic transmission — which disqualified them from receiving the high-performance N10 and GM3 options.
Firebirds optioned with T-tops received new Lexan plastic tops. The new tops were lighter in weight and tinted darker, but were more dome shaped and aged rapidly. GM replaced many sets with tops made of glass under warranty, but the Lexan tops continued as standard-issue through 1992. All Firebirds optioned with rear disc brakes now received PBR brake calipers and larger brake rotors, which resolved issues encountered with previous-model rear discs and increased stopping power. Introduction of GM's Vehicle Anti Theft System (VATS) or PASS-Key made all Firebirds more theft-resistant. The system was adapted from GM's higher-end Corvette and Cadillac vehicles in response to an escalating trend among car thieves to target the Camaro and Firebird. VATS incorporated a small resistor into the ignition key shaft which was read by a sensor when the key was inserted. VATS-equipped cars also displayed anti-theft system warning decals in the lower rear corners of the side windows. A new CD player was offered, shoulder belts were added in the back seat, and the convertible model carried over.
The Trans Am was selected to pace the Indianapolis 500, and Pontiac marketed another pace car replica. This special, 20th Anniversary Turbo Trans Am (TTA), based on the GTA, was only available in white with a tan interior, and came equipped with the turbocharged Buick 3.8L V6, originally developed for the Buick Regal Grand National. At the time, these replicas were as close to the actual pace car as any replica previously offered; the only differences between the replica cars and those that actually were on the track during the race were the additions of strobe lights and safety equipment to the latter. 1,555 were produced, 5 of those being test cars. Out of 1,550 cars produced by PAS, the actual pace cars were randomly selected and sent to Indy for testing and modification, and when the TTA was released to the public, they were underrated in power. Not all came with T-tops or with leather interior; there were hardtops and cloth-interior cars. But every TTA had an automatic transmission — the 2004-r. Still, the TTA was, at the time, widely regarded as the fastest production car in existence — ironically a title it had briefly (at least for 1989) usurped from its GM stablemate that had supplied the engine: the Buick Regal Grand National (although as noted above, the LB9/N10/MM5/GM3-equipped Formula was quite possibly a close contender as well). The five test TTA's, because they were for pre-production use, were pulled off of the assembly line without regard to color, and therefore were not necessarily white. At least two of these test cars were sold to private individuals, so there are at least two extremely rare, non-white, factory TTA's in existence; in fact, one is known to be red. Only three convertible TTA's were built by ASC, one of which was bought by the president of PAS, with the other two falling into private hands.
TTA Production Figures:
• 1,321 T-Top & Leather Interior
• 187 T-Top & Cloth Interior
• 24 Hardtop & Leather Interior
• 15 Hardtop & Cloth Interior (Base)
• 3 Convertible (prev. T-Top) & Leather int.
• 4 Test Cars with T-Top & Cloth Interior
• 1 Test Car with Hardtop & Leather Interior
1990
A driver’s side air bag was made standard. The Firebird interior again received a re-design, this time the changes were much less drastic: the lower dash and under-dash panels were altered, and accessory switches were moved to a new panel above the heater and radio controls. The console got a new shift indicator and different leather boot, steering wheel mounted radio controls disappeared from the GTA (due to the addition of the airbag), and the L98 engine was no longer offered in the convertible due to purported torque limitations in the unibody construction. LB9 and L98 platforms were updated with new speed density fuel injection, and the elimination of the MAF sensor reduced production costs and supposedly improved performance.
Like the Camaro, the 1990 Firebird only received a half-year production run, as Pontiac labored to release the re-styled 1991 model.
1991
All Firebirds received re-styled noses loosely fashioned after the "Banshee IV" show car while Pontiac was developing the all-new Fourth Generation platform. The Trans Am's ground effects were re-styled as well, and were made available on the base model Firebird. The Trans Am and Firebird Formula received a new fiberglass-constructed, flat, wrap-around wing, and all L98-equipped cars now received the N10 dual catalytic converters as standard. The Trans Am and GTA received updated two-piece tail lights with "PONTIAC" scripted in orange across the panels, and the center, high-mounted stop lamps were moved to inside the top edge of the rear hatch. The Firebird convertible was now being built on the same production line as the coup?s (previously, ASC had been converting customer/dealer ordered T-top cars, and the convertible option was not officially offered through GM), and was offered with one of three engine options: the LHO 3.1L V6, the L03 5.0L V8, or the LB9 5.0L V8. Production improvements led to use of new body sealants that improved body rigidity, long a source of complaints with the Third Generation F-body.
The new styling brought higher sales figures, up from the previous model year.
1992
This marked the final production year for the Third Generation platform, and as the Fourth Generation model was imminent, provided few changes for the Firebird. Mid-year, TPI-equipped cars only received blank throttle body plates rather than ones that had been marked "TUNED PORT INJECTION" on similar engines from prior model years; and black-painted valve covers replaced the silver components from previous years. As use of the L98 in the Corvette had come to an end, rough-cast runners found their way into L98-equipped Firebirds, and some cars received special rubber snubbers on the rear hatch frame that were designed to make the hatch more stable. Ultimately, very few Trans Ams, GTA's, and Formulas were produced in this model year, as most buyers were waiting for the next-generaion models.
Beginning in this year, a company named SLP Performance Parts modified a factory-built Formula into what they called the "Firehawk". Once a Formula had been order or purchased, this limited-availability option (RPO code B4U) could be specified, and the vehicle was sent to SLP to be modified. No two cars SLP produced were alike; they all were special orders. SLP had anticipated making 250 of these special Firebird Formulas, but in fact, only 27 were ordered; and of those, only 25 were ever built (numbered 1-25 for hardtops — with numbers 18 and 23 never being built — and the ONLY Firehawk Convertible was numbered 27). Of those 25 Firehawks, 21 were "Mandatory" Red, 1 Aqua, 1 White, 1 Blue, and 1 Green; 11 had the Competition Package, 3 came with Aluminum Engine Blocks, 1 had T-Tops, and as previously stated, 1 was a Convertible.
FIREHAWK SPECIFICATIONS
Standard Features: $39,995
• SLP modified 350 engine rated at 350 hp @ 5500 rpm and 390 ft•lbff @ 4400 rpm
• 17"X9.5" Ronal Rims with Firestone Firehawk SZ P275/275/40 ZR17 tires
• ZF 6-speed manual transmission with carbon fiber clutch
• Stainless catalytic converter exhaust system
• A performance Dana 44 rear axle with 3.54:1 Posi-gears
• Special Firehawk badging decals and numbered plaque
Competition Package: $9,995
• Cross-drilled 13 in Brembo Ferrari F-40 brakes
• Full roll cage minus the back seat
• Aluminum hood
• Recaro racing seats with full harnesses by Simpson and rear seat delete.
Engine:
• 4-bolt main engine block
• Forged steel crankshaft
• 1053 alloy, forged steel "Pink" connecting rods
• Light-weight, high-silicon, cast aluminum pistons
• Steel billet hydraulic roller camshaft
• High-output aluminum cylinder heads with stainless steel valves
• Port injection intake manifold designed by Ray Falconer
Performance:
• Weight-to-power ratio: 9.7 lb per hp
• Acceleration (0 to 60 mph): 4.6 seconds
• Quarter mile: 13.2 seconds @ 107 mph
• Top speed: 160 mph
• Skid pad: 0.88g on full tread