There are a couple of options, the easiest is to lube them, it's really easy, jack up the car enough you can get under it, ramps work pretty well. I put it on jack stands just easier for me, there are only 4 15mm bolts, 2 for each bushing. Take them out pull the bushing off lube the inside, I used synthetic grease from Amazon about $5. Put them back, I have read where people wrap the bar with plumbers Teflon tape, it will eventually wear away but should last all winter (calling BQbby the plumber). For about $15 you can get the Energy Suspension 34 mm polyurethane bushing for a 2005 Mustang, it is the exact same bushing as what was on my car after they did the TSB except poly and they use the stock brackets. It has channels (grooves) inside the bushing that hold the grease better. That is what is on my car now, no squeak. Then there are the Prothane bushings with a Zerk fitting so you can grease them without removing the bolts. I have a set of these to test but it has been to damn cold to put them on. Bottom line only one way to get rid of the squeak, and that is to lube the bushing, and you will most likely need to do this every fall at a minimum.
