I did a write up on my SPEC Stage3+ clutch in here in my rides thread and several other threads. I quite like it and it's cheap enough to buy. Bang for buck for sure!!
It's got a full face, cerametallic friction surfaces. Holds great. Is slippable in traffic and on hills. It has a sprung centre. Stock like feel. Great for the street. You dont need a left leg like Arnie to push it in either. It is softer underfoot and held much better than any other single plate clutch GSR/EVO I've driven with up to 300kw atw. I had 28psi and 330kw atw through mine and it was still holding on launches and hard pulls. I also did 10 runs down the strip on a hot 30+ degree day and it didnt smell not one bit like it was burning (unlike so many other clutches that cant handle the heat). Still to this day I swear by them as being the best clutch for a 300kw 4G63 to date at a cheap affordable price. When I had my engine out and inspected the clutch and my flywheel, there was no signs of heat discolouration, burning or warping on either one. I reckon it was the best decision I ever made to buy that clutch instead of going for a multi puck or heavy duty brass button Exedy piece of shit clutch instead. Seen way too many Exedy's fail and break springs in the clutch disc or simply just burn out and slip - they are totally over-rated in my opinion.
In saying that though and as much as I put the SPEC Stage3+ (the plus model) up high on the pedestal, I agree with the other boys. A big single wont handle the torque that 400kw atw AWD would be producing. I've even purchased a twin plate Competition Clutch thats still sitting on my shelf waiting for the day my big single decides to slip or the next time I have the engine or gearbox out - it'll be swapped out for CC twin clutch and flywheel setup.