If any of you are interested, it'* possible to upgrade the suspension on the Bonneville to be a stiffer, sportier ride. The Aurora which shares the chassis with the Bonneville came equipped with the FE3 suspension standard which is GM'* "sport suspension." The Bonneville SLE/SSEi came equipped with the FE2, or softer, "Touring suspension." I believe that the SE has the FE1, or soft ride, suspension. Anyways, It would be probable that suspension from the Aurora could be swapped onto the 2000+ Bonneville to achieve a stiffer, better handling vehicle. The sway bars are the same size however, at 30mm for the front, and 20mm for the rear. The Cadillac STS however, DOES have even larger sway bars that should be adaptable to the Bonneville. The rears are 22mm on the STS, but I do not know what the fronts are. Anyone wanting to try this out?

You have my interest about this subject. My car will probably need new suspension pretty soon anyways

Hey i got a buddy that was asking me how to improve his handling on his '05 Bonneville GXP just wondering how this worked out. Did the parts match up exactly or were there modifications required? Thanks for the info.

Your GXP will have FE5 suspension. As far as I know there really isn't anything to upgrade to from the GXP other than a full custom setup (i.e. modifying to use w-body KYB shocks, etc.).

Do miles on the sway bars matter as far as dependability or lasting effect?

As long as the vehicle they come off wasn't involved in an extremely bad accident (i.e. one end of the car pushed all the way to the cab) they'll be fine. The sway bars are just solid steel bars after all.

some bars rust and get soft though ive seen were they break after rusting enough