Thankfully as a track tester/reviewer of the TF kit I got a really good deal on it.
I must disagree that blowing air at the back face of the rotor via cutting the oem dust sheild, or the APR or PMU backing plates is a better design/more effective than sending the air into the center of the rotor and through the vanes. The latter is a well-established method in the racing world at cooling rotors much more effectively. There is lots of supporting data out there confirming this is the case. Why do you think Essex designed their Endurance kit mounting bracket to have the ducting direct air into the center of the rotors?
I applaud your efforts with your DIY solution but here's what I've found and how I've come to decide on the BBK. I've been fortunate enough to have a LOT of track time available when I'm instructing and I've gotten a lot more so far this year than I thought I would, with more still to go. I've not experienced abnormal wear on my rotors, in fact I've only recently in February installed my first set of new front rotors since installing the cooling kit last year with 10+ track days on the car.
The calipers are definitely not designed for the kind of heat I put them through on track. Even with titanium shims my dust boots can't take the heat and have begun to split around the pistons. Race pads with an 800*C MOT are getting so much heat into them they are glazing, crumbling away and wearing too quickly for my taste. I considered getting Winmax W7 or a slightly higher MOT race pad but they are still well over $200 a set in front and have a relatively thin friction puck in OEM sizing.
With my driving experience increasing I'm getting faster in the car, and with new coilovers going on soon my entry speeds will go up that much more and so will my braking demands. I have been progressively less confident with my OEM front brakes every time I track my car despite all the provisions I've made to them. Could I buy more expensive rotors and pads and try those out? Sure. But they wont have any more thermal capacity and that's where I've finally hit my breaking point (pun intended). I've gotten to the point where my cost for consumables is hurting me with all the track time I'm getting, and my confidence is still going down. The stock braking system isn't designed for track usage and the air ducting is simply a crutch for the system, which is not very thermally efficient at all by design. It has not solved the issue of my lack of braking confidence and it never will. There is only so much braking power a floating 2-piston caliper can deliver and the demand I'm bringing to them on track has far exceeded their thermal capacity. It took me a while to admit all this to myself but now that I can finally afford a BBK, I'm coming to terms with it all and deciding to cut my losses before getting too deep in consumables in an already inefficient system.
I'm admittedly a hard sale.
I must have read the Essex Sprint Kit product page 10 times over before I finally came to terms that the pros of the BBK far outweigh the one single con: high entry price. Cheaper, thicker pads, more compound variety, more braking power, no dust boots, huge increase in thermal capacity/efficiency, 20lbs overall unsprung weight reduction...etc. The bias also remains near stock as the piston sizes were custom from Essex with that requirement in mind.
Tracking this car has been a learning experience for me and a very rewarding one at that. I suspect you may have the same experience as I did with the stock brakes even with your cooling modifications after some more track time. Especially considering your car is supercharged and will see much higher entry speeds than mine right off the bat. Many others here would agree with me that if you're serious about tracking a forced inducted 86 then you need to provision your braking system accordingly with a BBK. A modified OEM braking system will only get you so far before your driving skills and braking demands exceed the thermal capacity of the system and you start wearing the weakest point of the system too quickly (the pads in my case); like I said before the ducts are only a crutch to an already inefficient system. In my case I am now over-provisioning my brakes for the sake of getting back my lost braking confidence, lowering my long-term operating costs and having the car ready for possible FI in the future. I won't need ducting anymore but I did order the GT3 air guides since they are cheap, easy, and definitely functional.
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CSG Mike , can I get an amen?