back in 1990 i had a 67 dart 340 and used the .528 purple lashed at .026 .028 it was real strong so then i thot the .557 would be better and a weekend later the .557 was out and .528 was back in,it had great street manners and pulled hard to 7200 but best was to shift at 6800 i still have it on the shelf made great racing memories with it.