These are Replacement Round Port Exhaust Springs by Hot Racing.

FEATURES:

Black Spring Steel Construction

INCLUDES:

Two Springs

REQUIRES:

Exhaust Header with Round Port

SPECS:
Manfold spring
Length:2.95" (75.0mm)
Coil Diameter: 0.20" (5.13mm)
Coil Length: 1.57" (40mm)
Return spring
Length: 1.44" (36mm)
Coil Diameter: 0.23" (6mm)
Coil Length:0.484" (12.0mm)