Hey TwoDogs,
 
Have you replaced the front tie rod ends to start with? I found mine had a fair bit of play which gave quite a vague feeling and it increased the bump steer feeling. 

My car is lowered on very stiff coilovers and I only notice bump steer when I go too long without a wheel alignment.

Good rule of thumb when looking at the suspension arms is that they should be at a 90 Degree angle from Vertical. 
if you go any lower the angle will decrease and this is when it becomes quite noticeable. 

Hope this helps

-Eric
 

Interesting topic. Mines always had a slight vibration at 95ish. I've never actively tried to solve it, as it's not too bad.

However the car has had the rack rebuilt, new tie rod ends, ball joints, coilovers, bushes and many tyres over the years. I've on occasion considered I may be increasing wear.

I really should look into it more.

Hi Eric,
 
 yes I had a tie rod replaced a year or so ago. I am having all components checked this week. I would not be surprised if the report comes back that ball joints, bushes and/or other tie rods should be replaced. You seem to be saying that the tire rods contribute to the bump steer. I am suggesting it is the other way round. Bump steer, if left, will create wear in the whole steering system..
 5sgte - I also had vibrations in my steering wheel, now solved. I needed hub centric rings plus discs machined. 2 separate vibrations.

My rotors have done less than 2000km. I however don't have hub centric rings installed. I do have an assortment on the shelf so I should experiment. Thanks, would be nice if it was smooth.

@5sgte - you don't need to experiment. The internal diameter is 62mm and the OD is... whatever you measure the big hole in your wheels.

Lol, I meant chuck some on and see if they fix the vibration.

TwoDogs
..so I got Koni inserts, which I like, with Eibachs, which have so far been too firm, but now I realise the bangs are probably not due to spring rate alone.

Which Eibach springs? 
Eibach Pro kits + Koni adjustables normally shouldn't ride hard according to most people's opinions.
How much front bump travel do you actually have, and have you measured it.
The early model bumpstops are thicker than the later model ones, so if you still have them, travel will be limited and the 'bangs' you mention could be the top of the shock crashing into the bumptops.

@Redtarga  - Eibach Pro + Koni adjustables is what I have and after thinking more about bump steer, I believe what you say about them not being too hard. Why I say that is because if 1 wheel hits a bump, I get a big yank of the steering wheel but the car goes over the bump just fine. It is when both wheels hit that the suspension travel is restricted  by the hubs which are unable to rotate around the steering axis in their bump steering fashion.
 I had a look at bump stops, thinking they were just a metal protection, but it seems they are 'clever' in max travel cornering situations. The situation I'm describing is going straight ahead.

From what I read, there is no point chasing bump steer or anything else until you have a solid base to start from. I wuld suggest doing the following.

• replaced all the bushes
• balljoints
• tie rods
• inner rod link on steering rack
• bushes for steering rack
• rear toe link rose joints
• checked the mounting points for cracks, broken welds
• checked the sway bar links as these bend and can 'lock' in certain circumstances

Once this is sorted, then you can start working on bump steer and general fine tuning of the car. 
 
Are you aware of how to test the bump steer? If not it is easy enough but does require a bit of work to set it all up. 
Also setting the caster right on the rear and front will settle the car. 
Then the camber
Then the alignment
Then check and do it three times to get it dead right.
 
 

Thanks B24,
 I got an inspection done yesterday and the report came back that I need:
 Left Front Wheel Bearing
 Both rear control arm bushes
 1 rear castor bush.
I had expected more especially in the steering rods, but I have already (<2000kms ago) replaced the left front outer tierod.
 I just posted on the Ordering Parts thread to see if a group buy for all the bushes was still happening.
 I will also be buying some bump steer correction bits to compensate for the 1" drop.