Ferrea valves are classed as being one of the best valves you can buy in the tuner market. They offer supreme quality and performance. They are available in standard compression and higher compression (flat face). The flat faced version will increase the compression ratio on a K series engine by between 0.2 and 0.3 of a compression ratio , which can be great if you are trying to run a slightly larger camshaft set on a stock bottom end. 

Set comes as 8 inlet + 8 exhaust valves 

5000 SERIES - FLAT FACE
Ferrea 5000 Series Valves are the most cost effective valve applications on the market today. They are designed to withstand high rpm and high spring pressure at a budget price. These valves are machined in Ferrea's state of the art CNC centers allowing tight tolerances without breaking the budget.

Features:
One-Piece Forging Stainless Steel
Proprietary Heat Treatment Process
Flat Face
Hard Chome Stems
Fully CNC Machined

6000 SERIES - DISHED FACE
Ferrea 6000 Series Competition Valves use a two-step slow forging process using EV8 stainless steel and are designed to provide excellent reliability in an environment of high spring pressures and roller cams at a budget price.
They have higher fatigue resistance and tensile strengths than their competitors's best offerings. These valve can also be used in Drag and Oval Track racing applications.