30.5mm(1.2") longer exhaust valve for the 2012 on 8 port head only
for use with special guides these are plasma heat treated to eradicate premature wear from unleaded petrol--For earlier heads see C-AHT376/7 valves.
The valve size has been reduced to its original homologated size which was actually measured as 1.15"- as it works better on the 2012 spec head
C-AHT376 & 377 early 8 port valve length 3.870" 98.298mm
New 8 port, from late 2012 length 3.933" 99.898mm