Well the only alternatives I can suggest that exist in 1mm oversized would to use either manley valves, or supertech valves.

Admin
I haven't tested it though I made 3 major changes in this build -

• 3SGE NA cams
• 1mm oversized valves
• 200cc additional capacity

I now make the same power as before though with 5psi less boost

Knowing that, do you have a set of factory valves you can drop back into the motor and use? This will get the car back on the track quickly and save you some money. It will also confirm if there is really a performance difference at the level of power the motor is making (It might well make a big difference on a motor like RobK's, but maybe not much on yours). If there is a power difference, you then know you need the bigger valves or you can wind the boost up a couple of PSI to compensate :)

I would have thought if the head had the seats changed or recut to suit 1mm oversized valves, then putting stock valves in would not have them seated correctly.

Knightrous, I was actually about to mention that I still have stock valves!

Seems you should be happy about that though... 
 
All seems (valve issues) very disappointing (not to mention heart breaking) really.

I've never wished I used oversize valves, I've heard of too many problems.

MCT_MR2
I would have thought if the head had the seats changed or recut to suit 1mm oversized valves, then putting stock valves in would not have them seated correctly.

Ah, didn't even cross my mind about that when suggesting on stock valves. In that case, back to spending $$$$

Lift is far more valuable than 1mm oversized valves. 

Can you pop a valve out then measure it? At least then you will know if the valves have 'grown' or 'stretched'. If they are no good, just get a set of supertech valves. It will not be expensive to buy a set of inlet valves. If they are the right length, better check the valve seats. That's about all I can think of.

I'd go back to Ferrea & see if they can do anything to help you out (like they did with Surok). They're aware of the issue & can replace or upgrade. Changing brand would hold the same level of risk.
 
Like Rob, I have standard valves & have no urge to change them personally. Doubt it'd  even be equivalent to even 1psi extra.