Best ifs kit? rms, hdk, gt suspension, or magnum force?

Also...hemidenny nor RMS have their respective specs posted on their website either....or at least I cant find them. So where's those specs
Pay attention! I'm not asking about RMS or HDK. Their stuff is already proven. I'm looking for validation not yet seen on the GST. If it's out there, great but I haven't been able to find anything.