Though i did buy a aluminum chassis for carpet, i tend to run mine box stock with;
1.3 front bar
Xray hard bumper
Ill usually run the stock springs much of he time, occasionally using he 25-28 progressives up front but no other option parts really.
I run mod with 6200 mah packs and car is super underweight and well balanced so i never bothered with the expensive screws. With the hard aluminum however i could see the lighter parts being of benefit, but prob only for stock.
Ive tried a ton of different settings and almost always end up back at kit. Cant really argue with it.