TT - I'm afraid that some of what you have posted is directly contradictory to what I have understood from a Senior Engineer at AP.
What, in particular, don't you agree with? 
Oh, and BTW, unlike the engineer at AP, I am not trying to sell you anything! 
....I don't wish to go into the details of my relationship with AP but suffice it to say that I am not subject to sales efforts and neither do I gain from sales of their products.
Oh, I'm not asking you to. It was partly a "tounge in cheek" comment. But it was also a basic "business" comment too, insomuch as AP are a commercial company, and need to sell stuff to make a profit. Part of one company achieving greater sales over a competator lies with the "visual appeal" or aesthetics, as well as functionality. Indeed, if aesthetics don't come into it, then no one would ever buy an Audi A3, and instead we'd all be driving Kia Rios, or other such hideous crap.
And it didn't even cross my mind that you were "associated" in any way with AP.
AP's Mk5 GTI big brake kit package has included conscious consideration of disc material, grooves or not, pad substance,
I agree. But you miss the point. Part of the "concious consideration" will be primarily with function, and another consideration will be the general asthetics, ie, making them visually appealing. I stand by my opinion that grooved discs offer absolutely no increase in efficiency. Put it another way, if grooves DID offer increases in braking efficiency, why arn't grooves used in Formula 1, or BTCC, WTC, DTM, LeMans endurance racers, GT racers, Formula Ford, A1 GP, Indy Cars, MotoGP, WSB, BSB, etc? Why arn't they used on Porsches, Bugatti, Bentley, Audi R8. I really think I have proven my case. Grooves are just added soley for purpose of style, and nothing else.
fluid type (amongst many other things).
Strongly disagree. Simple hydraulics. All fluids are in-compressible. Water, even urine would transmit the same force as old skool DOT3, the now common DOT4, or indeed any of the more fancy DOT5 and DOT5.1. The only advantage DOT5.1 has over DOT4 is a very slightly higher dry boiling point, and a noticeably better wet boiling point. However, the wet boiling point shouldn't even be an issue, if you have your brake fluid changed at the recommended intervals. Regarding the silicone based DOT5, well it wouldn't surprise me if it were actually made illegal for road use. A simple test on the MoT would detect that. Silicone brake fluids really are the work of the devil in road cars, and can cause considerably more hassle than they are worth.
To the "average" motorist, these fancy brake fluids are just snake oils.
I am not an engineer but various conversations with someone at AP with over 30 years experience specialising in brake technology plus my own experience of how well those brakes actually work on a car plus many many other driver's assessments of AP Racing's brakes, don't cause me to question what he has told me.
So, basically, you are an interested and enthusiastic bystander. Am I correct in assuming you have no qualifications in Automotive Engineering, or Automotive Maintenance.
And, with the greatest of respect, Robin, when have I ever questioned the efficacy of AP Racings brakes? For the record, I actually
praised them very highly! So please don't accuse me of "questioning" the efficiency and efficacy. I have merely stated a point of engineering fact on the grooves on discs, but at no time did I state that the grooves detracted in any performance in any way!
Oh, by the way, one of my college modules was actually set and examined by AP from Coventry, and I still have all their handouts and tutorials in my loft somewhere - so I am more than aware of the fundamentals of engineering, and particulalry the aproach which AP as a company take.
Consequently, T_T, I don't entirely agree with your posts about disc grooves, pad to disc material considerations, or benefits of fluid - In the case of AP Racing's product.
I'm not saying we should all agree on everything. However, if you are unable to offer specific information then we will reach a stalemate. Just like other members of this forum, I am here to learn too! But if you, for whatever reason, fail to offer specific "counter-claims", to specific areas that you claim to disagree with, then I'm quite sure that it will be more than just myself that will be left with an element of suspicion or confusion, when you rebut my opinion, but don't offer anything in return.
