Originally developed with the GM LT-1 engine specs in mind, these regulators were designed to keep these cars performing at their peak potential. These rail mount EFI regulators fit a variety of factory GM vehicles. Adjustable from 30-70 PSI. Fuel pressure rises on a 1:1 ratio when referencing boost. 1/8 in. NPT gauge port. Stainless steel spring, custom-designed for precise fuel control. A true billet regulator, CAD designed and CNC-machined. Return adapter may be replaced with P/N 15606 for a -06 return line (sold separately).