Suspension, wheel and fluid questions - Coupe q

[sdF <blood@mindspring.com>]

Hi all,

Just put on a set of 16" Borbet Type M wheels on the Coupe. Look fantastic, nice to have the wheels add to the look of the car instead of the crazed clearcoat on the Speedlines. Really nice wheel for not a lot of $$$, only bad thing is the center caps REFUSE to come off. Another story...

Anyway about 6,000 miles ago I installed Eibach springs and Boge Turbo Gas all around. I also put on a set of Yoko AVS S4 in the stock 15" size. I was noticing and increase in vibration whenever I would drive, even on glass smooth roads. I also noticed it felt like I was always "going over a bump" and noise inside the car was getting louder. I figured it was the front wheel bearings. I took it to a shop -which specializes in German cars- and they could find nothing at all wrong in the front end. I know it's more than me just being in tune with the car, what else would cause this rumbling? Switching to Dunlop Sport 8000s quieted the car down tremendously, btw.

Other suspension q - When going around a left hand turn unloading the driver's side, whenever I hit a bump it sends a shudder through the steering wheel. Does not do this any other time. 

Any ideas on these?

Finally, I'm going to replace all the fluids next weekend. I'll probably go with Redline. I remember a thread about this a few months ago, anyone have any particular thoughts on specific fluids, or should I just replace per owner's manual recommendations?

TIA,
Todd