You can fit the coppermix in an r34 gtt no worries.. Its has a great feel for a daily clutch but may be a little noisy - I've HAD NPC Clutch and highly recommend it, feels like a stock clutch and takes a thumping. I have an Exedy cushion button at the moment, pushing 268rwkw. I highly recommend it. it is NOT a "button" clutch, (Which is in and out) (this is hard to drive) You definitely drive it as a daily - I've been through a drift day and alot of street drifting and is still smooth
My recommendation is NPC organic or a exedy cushion button