1 & 3/8ths is the biggest sway bars for front and rear. I had em both on my car. the front one would not fit, without rubbing something. Honestly, from the bars I personally ran, I'd leave the front end alone. It's fine the way it is. A few mm's isnt going to help you out at all. As far as the rear, I have a pretty thick bar on my rear, unboxed trailing arms, and they're fine. Though, boxing them on any buick is pretty much mandatory for good handling. It's just a no brainer.
As far as a super tight regal, the things you can do, to make this car handle like no other, would be
A, new body bushings all the way around. These are the bushings that cushion the body on the frame.
B, New control/trailing arm bushings all the way around. Go with 1LE, and nothing too stiff, as you will get a touch of 'binding'.
C, Box all the rear trailing/control arms. Much stiffer that way.
D, New performance shocks all the way around. I use Bilstein, and they work very nicely. Ill never use another shock again.
E, new STOCK springs. These other stiffer, lower springs are ok, but they can be a bit much at times, and sometimes decrease the ride quality of a buick. Plus, if youre changing tires/rims, I'm not totally sure you want your car 1 inch off the ground either. Make lowering your car the last thing you do, if you do choose to do it.
F, put the really nice 'bolt on' rear swaybar on, like the one offered from HRpartsnstuff. I hear they're dam stiff.
G, use the energy suspension replacement endlinks for your front sway bar. Theyre pretty nice.
H, Frame braces. There's 4, from Kirbans. Part numbers 6756, 1586, 6744, and 6564. (these are actually pretty important, in that they keep your car from twisting the body, and cracking it in several places. Ive seen it time and time again.) And lastly, one of the most
important pieces in making a regal really handle, is the tires and rims. I myself, would go to the lightest aluminum 16x8" rim I could possibly find, and wrap em in the highest rated 'ultra high performance summer' tires I could find in that size. Most likely Yokohama or BF goodrich. You'd be really suprised in how much of a difference in grip and sidewall deflection a good tire makes. It's freakin night and day man. Trust me, don't listen to what the others say, when they say "regals will never ever really handle good" cuz that's just crap. Give me your car, and I'll show you different. Remember though, that the bigger the rim, the lower the aspect ratio of the tires. (sidewall height) sure, she'll corner like a lotus turbo, but the straight line ride quality will suck donkey ****. Don't do it. It's a buick. It's supposed to ride really nice. In suspension tuning, ya gotta find a good balance between handling and ride quality. Notice I didnt use the eibach lowering springs with +20% stiffness, tubular aluminum control arms all the way around, and 18" rims, with super low profile tires. sure the car would corner like a bmw M3, but again, it wouldnt ride like a buick would. I kept just a few minor things stock, so theres still a touch of vibration dampening goin on. My girls sunfire gt has a great suspension, and handles really nice, but it has nowhere near the softening ride of a buick though. I guess if your butts 18, you can suck it up, but when youre 35 or over, you dont wanna be playin games. You want a grown ups car, that rides like one too
Hope this helps.
(The only other mod you can do to your car, to make it handle like a dream, is to lighten it. It can make a difference in how your car accelerates, slows down, and corners. It's not that hard to shave 150 pounds off a regal. And if you REALLY want to save weight, you can start strippin' off power seat/window/antenna motors, usin fiberglass doors, and use aluminum heads and engine block. But I'm sure you don't wanna go that far lol. Hope this helps. )
