Now that I know the cause wasn't a valve failure I'm going with Supertech again. There's a few reasons for this.
The Ferrea valves have propierty locks which makes swapping not straight forward and adds cost.
I also want Inconel Exhaust Valves which ferrea don't do.

I want to swap my titanium retainers for steel ones and Supertech make them to go with my double springs.

Lastly I've been in contact with Supertech who are doing prices that no one else can get close to. $8 each for intake valves and $12 each for inconel exhaust valves. Plus $4 each for the retainers.

I.know many people that use Supertech and everyone speaks highly of them. So I'm willing to give them another go especially at those prices.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds