I've had nothing but great success from spec. Their drivability/durability is unmatched. I use their 4+ in a 3850lbs awd 630+hp car with literally over a hundred launches, 20k miles and still running strong. For a single plate clutch I won't ever buy anything else. Hence why I have one coming to go with the single I just bought.
335i 2009 665RWHP
Mod's: Vishnu/FFtec 6466 single turbo, VRSF exhaust, spec 3+
3000GT VR4 1994 647AWHP
Mod's: Fully built/forged block, twin TD-05's, Meth, and a whole lot of support.