Originally Posted by Fullpower

Daily driver, need the most reliable possible parts for towing far from home.

Originally Posted by Brian Tooley Racing

This (1500) series has all the benefits of the 1200 series springs plus an additional nitriding operation. The nitriding process, which is also done in-house, increases the strength at the surface of the wire and at the same time causes a slight softening of the core material. This trade-off in hardness results in a gain in endurance for the Circle Track and Road Circuit teams who are limited by the onset of fatigue at the wire surface. Since Drag racers are not limited by endurance, the loss of core hardness does not make nitriding suitable for their applications.