Even so, you still need electronic controls ... if you spray at too low of an rpm, you will almost certainly bend your connecting rods. In my experience, the guys that leave stuff like that up to chance, or a guestimate while trying to keep the car driving straight down the strip, are guys that end up prematurely rebuilding their engines.

Also, the purge kit is not for the bottle after you spray...it's for the lines before you spray, so that the power comes on right when you activate it (and with a semi-random delay a second or so later, after the lines have had the air pushed out of them).

You asked for advice on this thread, and for what it's worth, my advice is 100%+++ for sure to either: 1) not install nitrous, or 2) to be sure to install it with all of the proper electronic controls.
Titan Motorsports offers a good sway bar set, and the best strut tower bar is by TRD. TRD also makes sway bars, but they are heavier than the TMS set, and not adjustable.

Again, note that some of these modifications, like a stiff front sway bar or coilovers with a stiff rear spring rate, can make your Supra slower at the dragstrip. A car purpose-built for one application (eg drag racing) will always be significantly faster than the same car that was attempted to be built for all applications. If you want to be really fast at time attack, for example, I'd suggest you not worry about drag racing...or vice versa.
No one makes an Hbrace or a front splitter for the jza80 (Mkiv Supra chassis). In Europe, an active front spoiler was available, and several aftermarket body kit nose pieces come with a front splitter built in, such as the TRD widebody kit.

If you want advice as to how to invest your $ to ensure your Supra can take corners as fast as possible, invest in driver training at your local road course. A highly skilled driver in a crappy car will beat a mediocre driver in a great car every time, in pretty much any race event with turns. As they say, the best mechanical investment you can make in your car is to put some $ into the "nut behind the steering wheel". :)