D Deemo Full member Points 56 22 June 2009 #1 What does it mean wen they do a big valve upgrade to the head..
MasterAuron Very Senior Member Points 242 Location 379bhp 359lbft Car Mk1 Focus RS 22 June 2009 #2 Usually just the exhaust valves. Improves gas flow out of the head.
obi_waynne Administrator Staff member Moderator Points 1,157 Location Deal, Kent UK Car A3 1.4 TFSI 150 COD 23 June 2009 #3 All you need to know is here http://www.torquecars.com/tuning/intake-valves.php