Why is LRD the only company that sells a ket kit for the blaster.Almost all other sport quads still in production have jet kits.

 

No other companies offer jet kits for the blaster because the blaster can be tuned in just fine with standard Yamaha jets and needles.
A jet kit (like dynojet) provides you with a special tapered needle that fills the gap on modded machines where the stockers just won't due.
Companies like the one mentioned have power kits for the blaster...so they are going to try to sell you their jet kit to match the mods.
A most people do not spend a load of money doing serious upgrades to a blaster just so they can outgrow it in a couple of years....When one does take the plunge into upgrading the blaster...often the carb get changed at the same time...at that point you will be able to find the "kit" you need.