Which Gyro and Tail Servo would experts suggest for 450 Heli. Pls recommend with price and brand.

Spartan Quark Clear Edition + MKS DS95i

Or

Spartan Quark Clear Edition + KST DS215MG

Or

Spartan Quark Clear Edition + Turnigy 306g-hv

good luck! All three should lock in your tail. On the provisions you know how to properly operate a spartan quark gyro.

spartan quark or futaba 401 or hb790(quark clone).

or u can buy a avionic X5 or robird G31 and use them as tail only gyro and in future if u want to upgrade u only need to change ur head to go flybarless ....as both x5 and g31 are great gyros and cost almost same as a spartan quark or futaba 401