I have been using Scat single springs 2 years now but when took the head of for more modifications found one spring cracked. Snapped in half when twisting it by hand.
Thank god it didnt snapped totally in the dyno week before.
I have measured "gulmärkta" springs but too close to coil bind and too weak seat pressure in my opinion.
Using cheap springs is wrong place to save money,i get it now.

My other engine that im building habe Agap 272-13.3 cam and i allready have new set of those Scat Single HD:s but after one cracked with my daily driver with R-cam i need some better springs in that also.