Order Status & Returns
Gift Cards
Help Center
1-800-345-4545
Vehicle Info NeededPROMAXX PERFORMANCEPART NUMBER: 723-3150
XXTREME Bare 255 cc Cathedral Port Cylinder Heads for LS1, LS2 w/4 in. Min. Bore w/63 cc Combustion Chambers
$1,93143
Ships on 09/21/2026
Lowest Price GuaranteeLS1, LS2 w/4 in. Min. Bore [255 cc Cathedral Ports]
XXTREME Bare Cylinder HeadsLS1, LS2 w/4 in. Min. Bore 255 cc Cathedral Ports 63 cc Combustion Chambers Seats Installed for: 2.125 in. Int./1.60 in. Exh. Valves Valve Angle: 11° Requires LS3 Rocker Arms Set of 2
ProMaxx 3150 XXTREME Bare Cylinder Heads Features:
- High-flow as-cast port design
- Ultra-smooth 356-T6 aluminum casting
- 11-Degree valve angle
- Diamond honed guides
- Built-in raised valve cover rail
- .750 in. deck thickness
- For use with standard or 6 bolt pattern
- Large spring pockets
ProMaxx 3150 XXTREME Bare Cylinder Heads Notes:
- Requires 4 in. minimum engine bore
- Requires LS3 intake rocker arms
Emissions Note:
This part is only legal for sale and use on Uncontrolled (Non-Emissions Controlled) Vehicles or on vehicles used solely for the purposes of closed competition racing.
CLICK THIS LINK FOR IMPORTANT CARB & EPA EMISSIONS INFORMATION ABOUT THIS PART
Extreme Performance for LS Engines that Won't Break the Bank
ProMaxx EXXTREME Series aluminum cylinder heads for GM LS engines have runners and combustion chambers designed for maximum airflow.
Part TypeCylinder Head
Product LinePromaxx XXTREME GM LS Aluminum Cylinder Heads
BrandPROMAXX PERFORMANCE
Part CategoryPerformance Parts
Cylinder Head MaterialAluminum
Exhaust Valves IncludedNo
Locks IncludedNo
Engine Make/SizeGM Gen III/IV LS
Retainers IncludedNo
Intake Port ShapeCathedral
Guideplates IncludedNo
Cylinder Head FinishNatural
Intake Valve Angle11
Valve Seat MaterialSteel
FinishNatural
Valve Springs IncludedNo
Valve Seat Machine Style5-angle
Cnc-Machined Intake RunnerNo
Intake Valves IncludedNo
QuantitySold as a set of 2
Valve Stem Seals IncludedNo
Accessory Bolt Holes DrilledYes
Valve Guide MaterialManganese bronze
Combustion Chamber Volume (Cc)63
Exhaust Valve Angle11
Rocker Arm Studs IncludedNo
Cylinder Head StyleBare
Part FitmentSemi Universal
Valve Cover Mounting StyleCenterbolt
Intake Runner Volume (Cc)255
Cnc-Machined Exhaust RunnerNo
Cnc-Machined Combustion ChamberNo
Vendor Part Number3150
Package Qty1
Package TypeEA
No Questions
No Reviews
Items You Need
JEGS
Rocker Arm Set with Upgraded Trunnion Kit with Offset Intake Rockers for GM LS3, LS9, L92, and L76
Part Number : 555-20959
$39899$425.99
You Save$27.00
![GM LS Rocker Arm Bolts [8 mm x 1.25]](https://www.jegs.com/images/mini_200/500/555/555-83485.jpg)
![Valve Spring Compressor [Stud Mount]](https://www.jegs.com/images/mini_200/500/555/555-80518.jpg)
![Valve Spring Compressor [Stud Mount]](https://www.jegs.com/images/mini_200/500/555/555-80521.jpg)
![W89409 Valve Spring Compressor [C-Style]](https://www.jegs.com/images/mini_200/500/555/555-w89409.jpg)
![Engine Assembly Lube [4 oz. Bottle]](https://www.jegs.com/images/mini_200/500/555/555-28000.jpg)
JEGS
Premium 10-Blade Feeler Gauge Kit 0.015 in. to 0.035 in. (0.381mm to 0.889mm)
Part Number : 555-80502
$1777$20.99
You Save$3.22
JEGS
Valve Seal Installation Tool Works with 0.500" & 0.531" PC valve stem seals
Part Number : 555-80596
$4039$43.99
You Save$3.60
![Precision Cam Degree Wheel Kit [11 in.]](https://www.jegs.com/images/mini_200/500/555/555-81621.jpg)
JEGS
Cam Bearing Tool Set for Installation & Removal of Camshaft Bearings
Part Number : 555-80597
$19599$212.99
You Save$17.00
![1/2 in. Drive Torque Wrench [10 to 150 ft. lbs.]](https://www.jegs.com/images/mini_200/500/555/555-m200db.jpg)
JEGS
1/2 in. Drive Torque Wrench [10 to 150 ft. lbs.]
Part Number : 555-M200DB
$5239$56.99
You Save$4.60
![Breaker Bar [1/2 in. Drive, 30 in. L]](https://www.jegs.com/images/mini_200/500/555/555-w32126.jpg)
![Deep Well Impact Socket Set, 1/2 in. Drive [SAE 11-Piece]](https://www.jegs.com/images/mini_200/500/555/555-m590db.jpg)
JEGS
Deep Well Impact Socket Set, 1/2 in. Drive [SAE 11-Piece]
Part Number : 555-M590DB
$4699$51.99
You Save$5.00
![Deep Well Impact Socket Set, 1/2 in. Drive [Metric 11-Piece]](https://www.jegs.com/images/mini_200/500/555/555-m591db.jpg)
JEGS
Deep Well Impact Socket Set, 1/2 in. Drive [Metric 11-Piece]
Part Number : 555-M591DB
$4499$49.99
You Save$5.00
JEGS
Part Number : 555-20959
$39899$425.99
You Save$27.00
Some parts are not legal for use in California or other states with similar laws / regulations
