Rear spring need depends on how much your combined weight is.
The springs Blair offers are more then likely made by the same company. I have a close connection to that company and got my springs from him. Blair will take good care of you. He did so on the Elka shock buy-in.
2003 V - ASV C5 Levers, Univ. Solex bars, grip heaters, ktm mirrors, c.stand, SW Mo Engine grds,Two Bros, PC3, Garmin, Givi 460, tank bag, F. Extenda, BackOff, Super Brace, Elka Shock, Race Tech Gold. AWD/Mr.Ed's Moto seat mod. Dumonde Tech Racing Oil, Spider grips, Contour.
2001 KTM LC4 farkled (sold)