Quick answer: no Detailed answer: Xur's sparrow upgrades are only for the rare tier sparrows sold by the vanguard and crucible. All the upgrade does is increase the base speed to match a legendary tier sparrow and change the boost tail to whatever color upgrade you use on it. Its would be nice to be able to use the upgrades on any sparrow to at least change the tails color, like the blue upgrade on the arc runner sparrow league sparrow. The upgrades were only useful and soght after in year one when the only legendary sparrows available were the raid sparrows and that flame painted sparrow bungie gave us.

Puckish Rogue already answered your question, but this topic would belong in #destiny for future reference.

Only works on rare sparrows not legendary ones.