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5.3L LS-Carb vs. EFI
In looking at the two graphs, it is easy to dismiss the carbureted combination since the FAST LSX offered so much more power, but there is more to the equation than simple plots on the curve. The carbureted combination offered exceptional power for a 9.5:1 street motor displacing only 324 cubic inches. Note that the carbureted induction system was tuned more for low-speed torque production, as it out-powered the injection up to 4,100 rpm, where a great many street motors spend their time. The carbureted combo is also considerably less expensive and many enthusiasts simply won't run injection on their small-block. Who can argue with an aluminum-headed LS motor that offers 462 hp and 413 lb-ft of torque? For the power-hungry individuals, the FAST LSX induction system offered even more peak power and torque, checking in at 482 hp and 436 lb-ft of torque (more than a stock 6.0L LS2). Where the carbureted combo offered over 400 ft-lb of torque from 3,900 rpm to 5,900 rpm, the FAST LSX extended this torque production from 4,000 rpm to 6,300 rpm.