Best cylinder head
Where: Breaker’s yard
Vauxhall has tweaked the cylinder head design several times over the past 13 years. The early C16XE head (casting number: 90472726) is a cracker as it uses much larger ports, whereas the later X14XE and X16XE use smaller and different shaped ports that peg the power back. The very latest head casting (number: 90400187) uses triangular inlet ports, which work a lot better, gaining up to 12bp.