XFIª Spring & Phaser Mods Required Blower 237/248 Hydraulic Roller Finger Follower Cams for Ford 4.6/5.4L Modular 3V. Big power gains in mid to upper-RPM range for bolt-on blowers with high boost. Rough idle, solid power gains above 4900 RPM, requires spring & phaser upgrade. Custom tuning required. Best with 3.90+ gears & 3000+ stall.
XFI SPR Blower 237/248 Hydraulic Roller Cams for Ford 4.6/5.4L Modular 3 Valve
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