Many of the more complete handling kits, FRRP comes to mind - include swaybars which claim to help handling. I understand that the stiffer bushings will likely deflect less and give more road feel, but what is the bars relation to over/understeer?
I'm going to assume that the bushings you're talking about here are the bushings for the sta-bar and not for the control arms or the PHB. "Sta-bar" being shorthand for stabilizer bar, which is this part's correct name (common usage notwithstanding).
In a nutshell, as you stiffen the front bar (leaving everything else alone), you increase understeer. Likewise, stiffening only the rear bar reduces understeer.
Sta-bar bushings effectively reduce the effectiveness of the bar itself (it's a "springs in series" thing).
I have not tracked my car but have access to an open lot to play around. I know there are likely a lot of variables but my car seems to understeer at lower speeds, that tendency seems less the faster I go. Maybe this is because I am more likely to throttle up, I dunno.
I'm guessing that you're guilty of overdriving at the slower speeds. Cranking the wheel over too fast (tires can't quite keep up), going in too hot, staying on the brakes, etc.
Geometrically, a tight turn gives away more camber than a wider turn does, and you may not even have enough static negative camber dialed in to the car to begin with.
Tire inflation pressures - there are better settings than Ford's 32f/32r. Trust me.
Are the FRRP swaybars going to help my car handle better? Will it under or oversteer more? I know some are adjustable, how do they relate to initial turn in? Is it even worth the $ over the stock Brembo stuff?
Personally, I wouldn't ever get a non-adjustable bar when adjustable versions are available.
Kits that lack adjustment ask you to accept somebody else's definition of "improved handling" - and which need to consider a wider range of driver skill level. IOW, they'll tend to be a little on the conservative (understeerish) side.
I'm really new here, but not to the "corner-carving" stuff.
'08 GT coupe, 5M, wheels, tires, pads, fluid, a few suspension mods . . . still almost stock height
'19 WRX, 6M (hers)
'01 Maxima 20AE, 5M (spare, winter driver)