I have been researching on 2zz goodies and I seen MWR offers 9500+rpm springs and retainers. I looked into them and there Eibach springs rebranded with unknown retainers. Also MWRs valves are Supertechs. My question is will Brian Crowers retainers and Eibach springs hold the same rpm value. There $30 cheaper than MWRs. Besides noise is there really na/fi benefits I could look to down the road?