Ah, the good old Tazu debate.
We have good facts and figures we've collated to try and work out patterns and causes - the Master Cylinder (sold by XPart, but made by Tazu) seems to be very reliable overall and the copper pipe is fine as long as it's routed carefully.
The Slave Cylinder is where we've had issues, not helped by the extra noise the copper pipework fitted transmits (when used with a Metal Slave this is quite a lot worse) - there's a very fine line between a noisy bearing that's on the way out, and this extra noise transmitted once the rather attenuating plastic pipework is in the bin.
We'd love to have a solution to these, but the overall design seems to be a constraint we don't think we'll be able to work past - it's rather fundamentally flawed in terms of the seal / bearing design, and to be honest while we're absolutely confident in the quality of the Rear Upper Arms, redesigning a Slave Cylinder that includes a bearing is probably well above our skill level.
The OEM-Q Slave Cylinder we sell (we've been using this supplier for a couple of years now) seems to do the trick, but as with any Slave Cylinder for our cars they're not perfect and we do still have the odd failure reported to us.
Alas, that's just something we feel we'll have to live with - especially given the LUK item, Borg & Beck part and every other we've tried hasn't had a perfect record.
A massive shame for our cars, but in my eyes it's just one of those foibles we're stuck with.
On the bright side, we've still got buckets and buckets of the original AP Master Cylinder at around half the cost of the Tazu - these last like the originals, so should be good for 5+ years even with regular use:
https://www.dmgrs.co.uk/products/gen...04274fdc&_ss=r