I have a 87 325is, I am replacing the driveshaft and flex disk due to vibrations. Driveshaft is off and new on is here to install, While I am "in there" should I venture to replace the sub frame and trailing arm bushings? I have not had any issues...but well.. I have so much out of the way it may be a good time to do this, and replace those brake lines under the sub frame too (i have stainless elsewhere). If I am going to do this are the race bushings (Like the IE Blacks) going to be so harsh that I will not want to drive it on the street? This is mainly a DE car that I drive to and from the track, but I do some about town driving too. Thoughts and recommendations are appreciated I am an intermediate DE student doing 3-4 events per year.