I was talkng to a well known company that ports/ builds lots of S2K heads a while back and they said the stopped using the 1mm oversize (exhaust side I beleive) because it flows just as much with stock sized aftermarket valves.

I guess my question is are there any advantages in going with a 1mm larger valve on the exhaust side even though it flows the same?

 

no,Oem is good
just flows better if you bore out the Block more than it should do it justice.
if you get bigger pistons thus more cc
than you can open the head a little more i guess. and larger valves would come into play
in the end why even ask?

 

Benchtest numbers from Laskey (before & after) 1mm oversized exhaust

Exhaust flow is increased 13% - 14%.

 

Laskey was the people I was talking with, they said they now used stock size exhaust because it flows just as much.

 

I've done some research on this and larger exhaust valves with appropriate porting and bowl shapping can definately flow more than stock size with the same porting and bowl shaping. Even 0.5mm over on the exhaust can increase flow when done correctly.

 

yup i read the same and heard the same...since the F20 head is the finest OEM flowing head i think nothing much could be done there...test showed that a 0.5 flowed minor better than oem on the exhaust and that intake was good OEM..
now as i said when increasing the bore i think bigger valves would work just fine.