binhster

I actually did a test where I jacked up the rear end of my car with F-Sport sway and BCR and looked at the droop compared to my buddy's IS350 with the F-Sport sway and factory sport package suspension. Needless to say, the sport package drooped a little further. I didn't have a chance to measure my buddy's but it was clear that the OEM sport springs droop a little further (about ~1/2-3/4") which makes sense since the BCR assemblies are considerably shorter not to mention variable length depending on drop setting.
I ended up buying a used set of sport springs thinking that was the problem. Before going through with the install and buying shocks and whatnot, I decided to throw a different set of tires/wheels on the rear from my TL to see if the traction had anything to do with it. To my surprise, the different rubber helped and gripped better for the 45 degree temps at the time and car felt like it lifted less.
A month later, I installed a set of Continental DW 255/35/19 rear +225/35/19 fronts onto new wheels. From then on, the lifting problem seemed to completely dissapeared. Straight line traction is no longer a problem either. I'm positive that having a stiffer rear end negatively affects traction on start, but the stickier rubber completely makes up for it. I also think my older 255/40/18 DSG3 rubber hardened over time as well and cold temps for sure made things a lot worse. Last weekend, I did two days of lapping in Portland and the suspension proved to work really well. One of my biggest complaints though is VDIM kicking in in hard corners and preventing me from powering out of corners because it was taking throttle away until the rear end was sufficiently planted with traction to both rear tires. Each of these turns would take place around 40-60mph, so not something typically done on the street. I'm pretty sure VDIM is just too sensitive more than it being the suspension's fault. The only way to ever find out if the coilovers combined with F-Sport rear sway causes more lift is for me to swap the stock stuff back in and go try it out, but that would be wasted effort for what it's worth. Next time I'll turn off VDIM on the course and problem should be solved.

As for the clunking problem, it went completely away after setting the rear coils to full soft. It might make a slight hint of noise on cold mornings, but nothing that bothers me or even noticeable to untrained ear. I don't have a good explanation for this, but the stiffer compression/rebound setting caused all of the clunking noises.