Spec makes decent clutches... but they had a lot of teething issues with their mustang clutches and their f-body clutches... I will admit that I'm intrigued by their stage 5 clutch if they're claiming it'll hold 1800ftlbs.
all of their issues were with their sprung hub disks... and actually, now that I think back, I think they had some pressure plates letting go too. you don't hear that much negative about them on the mustang and f-body boards, but they caused a lot of damage when they were first starting out, and they didn't do ANYTHING to help...
my buddy had a Spec in his DOHC Cobra... pressure plate came apart, took out the bellhousing, transmission case, and BLOCK! (aluminum block... that was pricey because the car was only a couple years old at the time, and Ford told him to take a long walk as far as warranty)
like I said, I'm INTRIGUED by the thought of a $1000 single disk sintered iron clutch that'll hold that kind of torque, but I've gotta wonder about pedal effort, and based on past performance of the company, I've gotta wonder about inflated claims, product quality, and customer support.
with that said, the next clutch that goes in my truck will be another South Bend... if Peter's clutch lets you down somehow, he's likely to overnight you another one... if Spec's clutch lets you down, you're probably gonna be left holding your ____
Forrest