Additional features on the LSX intake included a modular design with removable runners for easy disassembly and porting, light-weight, composite construction for reduced heat soak compared to an aluminum intake and provisions for all the factory fuel rails and fittings. We added the FAST intake to this 5.3L on the engine dyno to see what kind of power it would add, but with the throttle-body bolted in place, this setup will not clear the front accessory drive when bolted into a truck. The new LSXRT is the only way to go for us truck guys, after all, the 'T' stands for truck. To maximize flow to the intake, the FAST LSX was combined with a 92mm MSD throttle-body. The original FAST (replaced recently by the LSXR) could be used with the factory 90mm or FAST 92mm throttle-bodies. FAST also produced an LSX for use with the smaller factory 75mm (three bolt) throttle-body. It should be noted, all of these throttle-bodies are cable driven and if your truck (usually '04 and newer) has a drive-by-wire throttle-body, these will not work on that application. One LSX intake feature we did not take advantage of was the nitrous bungs for use with a direct-port nitrous system. According to FAST, the LSX is worth an extra 15-18 wheel horsepower compared to the truck intake when tested on an otherwise stock 6.0L truck engine. All decked out with GenX 205 heads, TrackMax cam and LSX intake, our 5.3L LM7 was looking pretty sporty.

After bolting on the factory rockers, valve covers and damper, we were back in business and ready for some power runs with the new combination. Westech's Ernie Mena was on hand to run the FAST XFI management system, and in no time the new combination was tuned to perfection. Take a close look at how we made some serious power by simply bolting on some quality aftermarket components. Check with us next month as we upgrade the 5.3L short-block to a full 383 cubic inches using a stroker kit from Demon Engines and the new truck-specific LSXRT intake from FAST. Following the hike in displacement, we will finish up with the ultimate in torque production, a Vortech twin-screw supercharger.

5.3L LM7 POWER NUMBERS

RPM / HP - TQ (STOCK) / HP - TQ (MODIFIED)

2700 / 173 - 336 / NA - NA
2900 / 187 - 339 / 199 - 360
3100 / 202 - 343 / 213 - 361
3300 / 218 - 347 / 228 - 363
3500 / 233 - 350 / 247 - 371
3700 / 249 - 353 / 272 - 386
3900 / 267 - 360 / 293 - 395
4100 / 287 - 368 / 317 - 406
4300 / 305 - 373 / 343 - 419
4500 / 315 - 368 / 369 - 431
4700 / 328 - 366 / 390 - 436
4900 / 340 - 364 / 408 - 437
5100 / 344 - 354 / 426 - 439
5300 / 344 - 341 / 442 - 438
5500 / 345 - 329 / 458 - 437
5700 / 346 - 319 / 469 - 432
5900 / 341 - 304 / 476 - 423
6100 / 337 - 290 / 481 - 414
6300 / 330 - 275 / 482 - 402
6500 / NA - NA / 483 - 390
6700 / NA - NA / 481 - 377