Forced Induction Specs: Stock 2005-2009 Mustang GT ~ assumed with 300 RWHP (Explanation to charts below the information)
Actual results will vary. Data based off of company's advertised info. Most horsepower numbers are from dynos; most stock Mustangs have 260-280 hp to the wheels stock, so hp/$ ratio is slightly better than what is listed. Superchargers:
Brand Model - Type - Lowest psi HP - Highest psi HP - Intercooler? - Upgradeable? - Price - $/HP Ford Racing
400HP Kit - Twin-screw - 5 psi – 400 HP - * - No - Yes - $5930 - $59.30
550HP Kit - Twin-screw - 11 psi – 550 HP - * - Yes - Yes - $7029 - $28.12
Kenne Bell
Base 2.6L - Twin-screw - 5 psi – 471 HP - 6 psi - * - No - Yes - $4700 - $27.49
2.6L Big Bore - STAGE 1 - Twin-screw - 9 psi – 514 HP - 19.5 psi – 620 HP - Yes - Yes - $5800 - $18.13
2.6L Big Bore – STAGE 2 - Twin-screw - 9 psi – 522 HP - 19 psi – 675 HP - Yes - Yes - $6300 - $16.80
2.8 H Mammoth - Twin-screw - 10 psi – 540 HP - 25 psi – 775 HP - Yes - Yes - $6300 - $13.26
Roush
Base Roushcharger - Twin-screw - 5 psi – 445 HP - * - Yes - Yes - $5600 - $38.62
R2300 Kit - Twin-screw - * - 510 HP - * - 700 HP - Yes - Yes - $5900 - $14.75
Saleen
400 HP kit - Twin-screw - 4-5 psi – 400 HP - * - Yes - No - $5700 - $57.00
475 HP kit - Twin-screw - 5-5.5 psi – 475 HP - * - Yes - No - $6500 - $37.14
Whipple
Non-intercooled - Twin-screw - 6 psi – 415 HP - * - No - Yes - $5090 - $44.26
High Output system - Twin-screw - 11 psi – 500 HP - * - Yes - Yes - $6800 - $34.00
Edelbrock
E-Force - Twin-screw - 5 psi – 466 HP - * - Yes - Yes - $5800 - $34.93
Magnacharger
Magnacharger Intercooled - Roots - * - 425 HP - * - Yes - No - $5700 - $45.60
Paxton
Standard kit - Centrifugal - 8-9 psi – 420 HP - * - No - Yes - $4421 - $36.83
High Output - Centrifugal - 9-10 psi – 470 HP - * - Yes - Yes - $5680 - $33.41
Vortech
V-3 Standard Kit - Centrifugal - * - 420 HP - * - No - Yes - $4421 - $36.83
V-3 High Output - Centrifugal - * - 462 HP - * - Yes - Yes - $5684 - $35.09
ATI Procharger
High Output - Centrifugal - 10 psi – 540 HP - * - Yes - Yes - $5600 - $23.33
Stage II - Centrifugal - 10 psi – 540 HP - * - Yes - Yes - $5900 - $24.58
Turbochargers: Brand Model - Lowest psi HP - Highest psi HP - Intercooler? - Upgradeable? - Price - $/HP Hellion
Dual Turbo Kit - 5 psi – 380/11 psi - 500 HP - * - 650 HP - Yes - Yes - $7000 - $16.29
Hellion
Single Turbo Kit - 5 psi – 380/10 psi - 500 HP - * - 650 HP - Yes - Yes - $5000 - $14.29
STS
Single Turbo - 5 psi – 366 HP - * - 620 HP - No - Yes - $5944 - $18.58
Dual Turbo - 7 psi – 447 HP - * - 750 HP - Yes - Yes - $8000 - $17.78
Turbo Horsepower
Single Turbo Kit - 6 psi – 467 HP 12 psi – 595 HP - No - Yes - $4000 - $13.56
Twin Turbo Kit - * - * - 750 HP - Yes - Yes - $7400 - $16.44
HP Performance
STAGE 1 Single Turbo - 8 psi – 469 HP - * - 600 HP - Yes - Yes - $4500 - $15.00
STAGE 2 Single Turbo - * - * - 750 HP - Yes - Yes - $5000 - $11.11
STAGE 3 Single Turbo - * - * - 900 HP - Yes- Yes - $5345 - $8.91
STAGE 1 Twin Turbo - * - * - 750 HP - Yes - Yes - $6400 - $14.22
STAGE 2 Twin Turbo - * - * - 850 HP - Yes - Yes - $6900 - $12.54
STAGE 3 Twin Turbo - * - * - 1000 HP - Yes - Yes - $7900 - $11.29
Exile Turbo
Stealth Twin Turbo - 8 psi – 440 HP - * - 900 HP - Yes - Yes - $10000 - $16.67
Blow By Racing
Single Turbo - 7 psi - 450 - 15 psi – 650+ HP - Yes - Yes - $6300 - $18.00
Granettelli Motorsports
Single Turbo - 6 psi – 370 HP/16 psi – 650 HP - * - 800 HP - Yes - No - $6600 - $13.20
Power House
PipeLine Single Turbo - * - 450 HP - * - 675+ HP - Yes - No - $6000 - $16.00
Turbonetics
Single Turbo - 8.5 psi – 550 HP - * - Yes - Yes - $6400 - $25.60
Impulse Engineering
Twin Turbo - 8 psi - 480 - * - 1200 HP - Yes - Yes - $8500 - $9.44
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* - unavailable
- The lowest/highest psi advertised/known HP gains. The highest HP gains are with built engines, etc (no N2O).
- Upgradable means if the F/I unit can be upgraded with larger intakes, intercooler, etc.
- Most common advertised price; many sites offer better prices.
- The horsepower/dollar ratio is calculated based on max advertised HP gain. The formula is “total cost ÷ HP gain”.
- Most units have a higher max HP capability than listed. The highest HP gains known are listed.
TOP PERFORMERS: Horsepower per psi: Kenne Bell base 2.6L - 34.2 HP/psi; Turbonetics Single Turbo - 29.41 HP/psi
Max HP capability: Kenne Bell 2.8H Mammoth – 775 HP; Impulse Engineering – 1200 HP
Best value ($/HP): Kenne Bell 2.8H Mammoth ($13.26/HP); HP Performance – STAGE 3 Single Turbo ($8.91/HP)
PROS + CONS Component - Supercharger -- Turbocharger Cost - Generally high -- Some cases low; some cases very high
Lag - Little to no lag; produces boost at very low RPM -- Exhaust must spool up before boost; on today’s 4.6 V8, spools very quickly
Efficiency - Runs off power from the crank; robs power from the engine; can sometimes increase mpg -- Reuses “wasted” exhaust gasses; less parasitic drag when impeller isn’t spinning & can increase mpg
Heat Intercooler required on some applications; still gets hot Intercooler required almost definitely; runs very hot (rear-mounted turbos have less under hood heat)
Surge - Generally continuous power -- Once turbo spools up, huge surge of power
Backpressure - Not much more than stock -- Exhaust flow is interrupted by turbine
Noise - Generally much noisier than stock all the time (whine) -- Not much louder than stock depending on application (located in exhaust); only noisy when boost kicks in
Reliability - Doesn't require warm-up/cool-down time; can throw belts and cause damage to other engine components -- Requires warm-up/cool-down time; very high RPMs; residual oil; higher heat; fewer mechanical and moving parts
Ease of Installation - Usually very simple; few pieces; somewhat difficult to do regular engine maintenance -- Generally complex; many components
Maximum power output - Limited; depends on size -- Can reach very high RPMs; outrageous peak boost numbers; huge peak power
Tune-ability - Generally easy to tune because of simplicity of design; needs different pulleys for different boost levels -- Many components which require extensive and generally difficult tuning; easily change the boost level
Gas Mileage - Generally decrease mpg because they run off the engine (parasitic loss) -- Can increase gas mileage because they make the engine more efficient and don’t take power from the engine
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Summary
All in all, turbochargers are
pretty much a better buy for the money if you plan on going
BIG. Nearly all turbochargers have the capability of reaching unbelievable amounts of horsepower (not to mention torque!) that most superchargers are not capable of (there are a few exceptions).
Not everyone needs a turbocharged monster and for many a supercharged or "lower-level" turbocharged
Stang will offer more than enough power to keep them happy and smoke some ricers while at it!

This is a very opinionated topic... However, both superchargers and turbochargers are guaranteed to make a stock S197 4.6L V8 Mustang GT kick some serious ass!
Thanks for reading! Hopefully this has been of some help for you!
