A magazine dynoed a bunch of catbacks on a WRX a while back. The results would be about the same on an STI.
Factory Subaru
Manufacturer Factory Subaru
Type Stock
MSRP $715.00
Weight 37.4 pounds
Tip Diameter dual 72mm tips (2.834 inch)
Sound Decibel @ Idle 87dB
Sound Decibel @ 3000 rpm 86dB
Peak Horsepower 191. 8 Hp @ 5600 rpm
Peak Torque 197.1 Tq @ 3800 rpm
Largest Horsepower gain over stock N/A
Largest Torque gain over stock N/A
Piping Diameter 52mm (2.047 inch)
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5Zigen
Manufacturer 5Zigen
Type Fireball
MSRP $700.00
Weight 31.3 pounds
Tip Diameter 100mm (3.937 inch)
Sound Decibel @ Idle 98 dB
Sound Decibel @ 3000 rpm 105 dB
Peak Horsepower 198.7 Hp @ 5625 rpm
Peak Torque 201.3 Tq @ 4400 rpm
Largest Horsepower gain over stock 12.0 Hp @ 4400 rpm
Largest Torque gain over stock 13.7 Tq @ 4400 rpm
Piping Diameter 70mm (2.756-inch)
Exhaust System Construction Polished stainless steel canister with coated mild-steel piping.
Source 5Zigen USA, Inc., (310) 608-5575
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Manufacturer Tanabe
Type Racing Super Medalion
MSRP $650.00
Weight 24.0 pounds
Tip Diameter 100mm (3.937 inch)
Sound Decibel @ Idle 101 dB
Sound Decibel @ 3000 rpm 107 dB
Peak Horsepower 197.7 Hp @ 5600 rpm
Peak Torque 199.6 @ 3600 rpm
Largest Horsepower gain over stock 8.7 Hp @ 4200 rpm
Largest Torque gain over stock 10.1 Tq @ 4200 rpm
Piping Diameter 70mm (2.755 inch)
Exhaust System Construction Polished stainless steel canister with stainless steel piping.
Source Mackin Industries (Tanabe Distributor) (562) 946-6820
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Manufacturer Blitz
Type Nur-Spec Racing
MSRP $698.00
Weight 37.2 pounds
Tip Diameter 115mm (4.527 inch)
Sound Decibel @ Idle 104 dB
Sound Decibel @ 3000 rpm 103 dB
Peak Horsepower 200.2 Hp @ 5600 rpm
Peak Torque 204.2 @ 3725 rpm
Largest Horsepower gain over stock 13.9 Hp @ 4400 rpm
Largest Torque gain over stock 15.3 Tq @ 4400 rpm
Piping Diameter 80 mm (3.150inch)
Exhaust Construction Polished stainless steel canister and piping
Source Blitz North America, (714) 777-9766
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Manufacturer GReddy
Type Evolution
MSRP $699.00
Weight 37.4 pounds
Tip Diameter 115mm (4.527 inch)
Sound Decibel @ Idle 94 dB
Sound Decibel @ 3000 rpm 92 dB
Peak Horsepower 200.9 Hp @ 5600 rpm
Peak Torque 201.6 @ 4600 rpm
Largest Horsepower gain over stock 9.8 Hp @ 4600 rpm
Largest Torque gain over stock 10.6 @ 4600 rpm
Piping Diameter 80mm (3.150 inch)
Exhaust System Construction Polished stainless steel canister with coated mild steel piping
Source GReddy, (949) 588-8300
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Manufacturer Cobb Tuning
Type N/A
MSRP $575.00
Weight 26.6 pounds
Tip Diameter 90mm (3.543 inch)
Sound Decibel @ Idle 97 dB
Sound Decibel @ 3000 rpm 103 dB
Peak Horsepower 200.0 Hp @ 5600 rpm
Peak Torque 202.7 @ 4000 rpm
Largest Horsepower gain over stock 12.6 Hp @ 4400 rpm
Largest Torque gain over stock 14.1 Tq @ 4400 rpm
Piping Diameter 75mm (2.952 inch)
Exhaust System Construction Polished stainless steel canister with stainless steel piping.
Source Cobb Tuning, (972) 771-1555
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Manufacturer Supersprint
Type N/A
MSRP $850.00
Weight 29.0 pounds
Tip Diameter 90mm x 145mm Oval Tip (3.54 inch x 5.70 inch)
Sound Decibel @ Idle 95 dB
Sound Decibel @ 3000 rpm 101 dB
Peak Horsepower 198.0 Hp @ 5700 rpm
Peak Torque 201.3 Tq @ 3700 rpm
Largest Horsepower gain over stock 12.2 Hp @ 4400 rpm
Largest Torque gain over stock 13.7 Tq @ 4400 rpm
Piping Diameter 63.5mm (2.500 inch)
Exhaust System Construction Polished stainless steel canister and piping
Source Supersprint, (800) 648-7278
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Manufacturer HKS
Type Hi-Power
MSRP $670.00
Weight 30.7 pounds
Tip Diameter 120mm (4.724 inch)
Sound Decibel @ Idle 97 dB
Sound Decibel @ 3000 rpm 102 dB
Peak Horsepower 202.9 Hp @ 5625 rpm
Peak Torque 204.9 Tq @ 3650 rpm
Largest Horsepower gain over stock 13.1 Hp @ 5620 rpm
Largest Torque gain over stock 13.6 Tq @ 4200 rpm
Piping Diameter 75mm (2.952 inch)
Exhaust System Construction Polished stainless steel canister with
[email protected] mild steel piping.
Source HKS USA, Inc., (310) 491-3300
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Manufacturer A'PEXi
Type GT Spec.
MSRP $749.00
Weight 26.2 pounds
Tip Diameter 115mm (4.528 inch)
Sound Decibel @ Idle 100 dB
Sound Decibel @ 3000 rpm 104 dB
Peak Horsepower 201.1 Hp @ 5625 rpm
Peak Torque 201.5 Tq @ 4600 rpm
Largest Horsepower gain over stock 9.9 Hp @ 4600 rpm
Largest Torque gain over stock 10.6 Tq @ 4600 rpm
Piping Diameter 75mm-85mm (2.953-3.346 inch)
Exhaust System Construction Polished stainless steel canister and piping
Source AÕPEX Integration (714) 685-5700
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Manufacturer Skunk2 Racing
Type N/A
MSRP $599.00
Weight 30.6 pounds
Tip Diameter 100mm (3.937 inch)
Sound Decibel @ Idle 102 dB
Sound Decibel @ 3000 rpm 106 dB
Peak Horsepower 199.3 Hp @ 5625 rpm
Peak Torque 203.6 Tq @ 3600 rpm
Largest Horsepower gain over stock 13.0 Hp @ 4400 rpm
Largest Torque gain over stock 15.7 Tq @ 4400 rpm
Piping Diameter 75mm (2.953 inch)
Construction Polished stainless steel canister with stainless steel piping.
Source Skunk2 Racing, (909) 808-9888
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Manufacturer MRT Performance
Type N/A
MSRP $795.00
Weight 30.5 pounds
Tip Diameter 100mm (3.937 inch)
Sound Decibel @ Idle 96dB
Sound Decibel @ 3000 rpm 104 dB
Peak Horsepower 198.8 Hp @ 5700 rpm
Peak Torque 202.8 Tq @ 3675 rpm
Largest Horsepower gain over stock 13.6 Hp @ 4400 rpm
Largest Torque gain over stock 15.5 Tq @ 4400 rpm
Piping Diameter 75mm (2.953 inch)
Construction Polished stainless steel canister with stainless steel piping.
Source Renick Motorsports (MRT Dealer), (714) 871-9300
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Manufacturer M2 Performance
Type N/A
MSRP $795.00
Weight 34.9 pounds
Tip Diameter dual 76.2mm (3.00 inch)
Sound Decibel @ Idle 94dB
Sound Decibel @ 3000 rpm 94dB
Peak Horsepower 195.9 Hp @ 5700 rpm
Peak Torque 198.9 Tq @ 3675 rpm
Largest Horsepower gain over stock 7.1 Hp @ 4200 rpm
Largest Torque gain over stock 8.7 Tq @ 4200 rpm
Piping Diameter 76.2mm (3.000 inch)
Exhaust System Construction Polished stainless steel canister with stainless steel piping.
Source M2 Performance, (925) 686-9047
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Manufacturer Thermal Research & Development
Type N/A
MSRP $694.95
Weight 26.2 pounds
Tip Diameter 80mm x 111mm (3.150 x 4.370 inch) oval tip
Sound Decibel @ Idle 101 dB
Sound Decibel @ 3000 rpm 108 dB
Peak Horsepower 198.3 Hp @ 5700 rpm
Peak Torque 201.1 Tq @ 4300 rpm
Largest Horsepower gain over stock 11.4 Hp @ 4400
Largest Torque gain over stock 13. 4 Tq @ 4400
Piping Diameter 76.2mm (3.000 inch)
Exhaust System Construction Polished stainless steel canister and piping.
Source Thermal Research & Development, (818) 998-4865
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