PRC 247cc CNC Cathedral Ported Cylinder HeadsPrecision Race Components all new cylinder head castings completed with 247cc runners. For 408 cubic inch and larger applications with 4. 03"+ bore sizing. Features: 247cc Fully CNC Ported Intake Runners 84cc Fully CNC Ported Exhaust Runners TSP . 750 Spring Kit w PAC Valve Springs & Titanium Retainers 68cc CNC Machined Chambers CHE Bronze Guides 2. 120" Hollow Stem Intake Valves 1. 600" Stainless Exhaust Valves Factory Rocker Friendly!!* The all new

and an optional fitting is available for use with factory fuel lines

* Plug-and-play compatible with more Holley EFI accessories* Available with or without a 3

They give you complete charge of your engine and self-learning fuel strategies

Perfect fit for LS1

X-Series Wideband UEGO AFR Controllers Gauge were fastest responding wideband air/fuel ratio controllers in an independent test vs

You may need to change to a different length pushrod if you change to a different style of lifters

Product Line:  PAC Racing 1200 Series Valve Springs

SOLD AS SINGLE (PER EXTENSION)

Note: Y-Pipe will work on trucks & suv's with 6 Speed & 8 Speed Automatic transmissions

GMC Sierra

Pedal Commander’s 4 modes and 36 presets will be indispensable

68% Efficient @ 653 CFM