I was thinking that you were NA, but you really have to pick the final purpose and goal of your car.
If you need to do a single stop from 140mph on an NA car, then a decent set of pads and rotors on the stock calipers should work fine.
If you are going to do multiple back to back stops from 140mph, often tracking some beastly turbo car - the best way to ensure braking is spend the money on 4 piston calipers, a pad that can handle higher temperatures than Hawk (do the research for whatever pads fit the calipers that you buy. Aftermarket caliper brands tend to have better friction/temp curves than OEM caliper replacement pad options), and get a quality set of rotors (my preference is not drilled if possible with better internal fin design).
If budget is primary concern, you may be able to cheap out stock calipers, on some unknown shitty rotor, with a completely track oriented pad (if they make one for IS300) that can maintain some amount of friction at super high temperatures (not Hawk or anything similar). The trade-off is that kind of pad will be noisy as hell, dusty, and have almost no friction when cold and be dangerous on the street because of it.
You make the really aggressive pads safer on the street by going with 4 piston calipers. The extra hydraulic force helps when it's cold because 4 times almost no friction is better and hopefully enough to stop the car (or at least moreso than 2 times almost no friction when cold).
The problem is that the amount of friction a pad generates changes with temperature. There is no magical binder for the pad compound that performs at every single temperature. Pick your goal, pick the suitable compromise and buy the right set up.
If multiple 140mph stops isn't a concern, then for $100-$400 for a set of performance pads, I'm not quite sure how you would be enraged if the solution didn't work given the alternative will be much more?
Originally Posted by PhoenixLexi300
I forgot to mention tires are sport comp 2. I'll be switching to proxes r888. But anyway the tires are pretty sticky. Not just regular passenger tires.
As for the date on the fluid, I didn't check. Just purchased it and flushed it in.
No problem purchasing hawk pads, I'll just be ENRAGED if my brakes still suck with hawk pads.
I'm trying to determine #1 if my current setup has a problem and if corrected will my brakes be sufficient?
And #2 if the stock setup is functioning properly with premium pads etc is it enough to stop me 140 mph down to 40mph for turns?
Where do I decide if bbk is necessary? After I get the brakes dialed in I'm boosting the motor to 450 @wheels. So it's imperative I can stop.
If I'll absolutely need a bbk for that speed and my heavy car i don't want to mess with any more stock options.