Does anyone know if true lightweight rotors exist?

Well this probably doesnt help you, but i was reading about F1 cars actually using carbon fiber disks!! That's pretty sick IMO.

Strange makes them. There's another company that makes them but I can't remember who it was. And both kits are expensive.

Pete - the rear brakes on a front heavy car like the stang do very little work in actually stopping the car. That's one reason the rear rotors are so small/light. They simply don't need to be very stout. Especially with a stock-style suspension that allows a lot of nose dive - most of the work of stopping the car takes place at the front.

And I've got news for you - if you check out the larger rotors that folks put on the front (13" rotors and such) they're probably heavier than the stock rotors just because of the diameter increase alone. The extra weight is not all downside - the more mass the rotor has, the more heat it can absorb/reject without getting to temperatures that are too high for effective braking. So don't go too crazy on your light-weight rotor thoughts. The carbon rotors referred to earlier work because they don't lose braking efficiency at extreme temps like the metalllic rotors do. And yes they are light. And yes, they are EXTREMELY expensive. An F1 braking set up alone would cost way more than most of our cars do. Keep in mind - that's an issue for F1 primarily because the rules dictate they have to run a 13" wheel - so their rotors are extremely small.

Grooves/drilling rotors - those were come up with because in the past, when the pad was pressed against the rotor (pressure, heat, friction) it gives off gases. In the old days, pad compounds were such that the gas could actually form a boundary layer which inhibited the build up of friction and limited braking effectiveness. The grooves or holes allowed the gas to escape which prevented the problem. It's identical to what happens when a tire hydroplanes on water - except instead of grooving the pad (tire grooves), they 'groove' or drill the rotor. However, pad construction has changed over the years. With most quality contemporary pads in street use, it's not an issue any longer - and so, grooves and drilling on street cars are more about bling than anything else.

But here's the real kicker - the brakes don't stop the car. The tires do. So be sure you've got enough wheel/sticky tire on the front of the car -- for a single hard stop (emergency stop on the street) - that's the best gain you can make in stopping power. If your front brakes will lock up your front tires, then bigger brakes won't stop you any sooner for the first stop. They will help you stop short multiple times, while the stockers get overwhelmed with heat (like on a road course with continual lapping) - but on the street - if your brakes will lock up the tires, then big brakes are pretty much bling too.

Descaling the vented part of your rotors was a fine idea - despite your subjective measurement of the results, I doubt you removed more than an ounce or two of weight. But you probably helped the rotor with it's ability to transfer heat to the air (like cleaning the bugs out of your radiator fins) and that helps braking performance in terms of putting off brake fade for a longer period of time.

What about aluminum drums for the rear? I have heard of them for these cars but nobody really has any weight specs. I made a post on the Corral awhile back and didnt get the weight numbers I was looking for.

There are lightweight brake kits for the cars though, Aerospace is a popular drag type setup, there are quite a few different cars around here running them.