There's a lot of engineering in what at first seems to be a simple spring. Resonant frequencies, coil bind, spring pressure seat pressure. I'm sure its no news to you. I'd be looking closely at what they offer relative to the bigger names in valve springs, and comparing tech specs as best you can. That being said, buying a big brand spring and copying it might not maintain all the metallurgical properties that are the 'trade secret' intellectual property of that manufacturer. You could just get them and take a gamble... what's the worst that could happen Is this for the race car? What sort of RPM do you get it to? If you pull it down every season, it might be good to get measurements before/after.
