That depends on your goals. I have a KB 2.6 on a stock block. When I installed it I added 60lb injectors, KB Boost a pump and a MAFia. My goals were to push the stock block as far as possible so I also installed long tube headers with 3" exhaust and a forced cold air intake. As I turned it up I added 255 lph fuel pumps.
Kenne Bell 2.6 - JLP Forced Air Induction - MAFia - JLP Thunder Tube - 60 lb Injectors - Kenne Bell Boost A Pump - Afco Heat Exchanger - Walbro 255 Fuel Pumps - Accufab SBTB - Denso Plugs - JLP IC Reservoir - PI Stall Converter - Weapon X cops - Factory Tech Valve Body - JLP Comp R Exhaust - QA1 Shocks - Beltech Drop Springs - PST CF Driveshaft - Flex Form Fiberglass Leafs - JLP Shackles - Hotchkis Sway Bars - JLP Traction Bars - RotorPro Brakes - Aeroforce Interceptor Gauges - DiabloSport Predator - JLP Dyno Tune - Detroit Truetrac - Forte and Grabbers - Bogarts and Hoosiers