Manley GM LS Series Super Finished H.P. Valve Springs .650 Max Lift (16 Pieces) Jennifer Aniston Steps Out After Donating $1 Million to Puerto Rico. From drag strips to short track and endurance circuits, the Manley NexTek series is engineered for serious racers. NexTek springs resist pressure loss and valve train degradation even in the most demanding race conditions. That means more consistent spring force deep into a run, reduced valve bounce, and improved overall stability for high RPM performance. Built to outperform and outlast in real world competition.